Lead bullet pressures are greater than jacket bullet pressures of the same weight

[10mmShooter]

Here is an interesting tidbit...I would have assumed the opposite.

Here is a quote off the Western Powders blog from their ballistics labs:


http://blog.westernpowders.com/2014/04/dear-labby-questions-customers-ask-our-ballistics-lab/

Lead Bullet Pressure

Actually it is a general question: All things being equal do lead bullets generate more pressure than jacketed bullets?

Yes, they do. It all comes down to the frictional co-efficient. Gilding metals like copper slide more readily than lead does on a steel surface. You can write your name on a piece of paper using a lead bullet much more readily than you can with a copper one. This tendency to smear, which is why it leaves a track on paper is also why it tends to grab the barrel more quickly and increase pressures. Using jacketed bullet data with a lead bullet of the same weight will result in higher pressures, everything else being equal.

[randyrat]

It may sound like common knowledge, UN arguable. I don't think like that and your not taking BOOLIT lube in to consideration in the equation. I'm going against the experts on this one and could be dead wrong.

[geargnasher]

{shaking head in disgust}

Gear

[randyrat]

I know one thing most of my boolits don't leave any lead smeared inside the barrel EVER, some for years...The other thing, most of my guns have to be cleaned after using jacketed bullets eventually. (if I used a jacketed bullet)

[LynC2]

I may well be wrong and it wouldn't be the first time. If leaving a lead smear on paper shows it has a higher coefficient of friction, then the graphite in a pencil must really be high! Also try pushing a jacketed bullet through a barrel and compare that to a lead one.

[Dutch4122]

Here is an interesting tidbit...I would have assumed the opposite.
Here is a quote off the Western Powders blog from their ballistics labs:
http://blog.westernpowders.com/2014/04/dear-labby-questions-customers-ask-our-ballistics-lab/
Using jacketed bullet data with a lead bullet of the same weight will result in higher pressures, everything else being equal.

Quickload will show you what the real differences are. Western Powders has it backwards.

[Larry Gibson]

[smilie=b::not listening:

With all the ability to measure pressure these days. ........

Larry Gibson

[Bullshop]

In my experience all else being equal a cast lubricated boolit will give lower velocity of in the neighborhood of 150 fps depending on the type of load and cartridge.
Since I can not accurately measure pressure but can accurately measure velocity I use velocity as an indicator of pressure.
In my own observations lower velocity reads as lower pressure.
Another point I would like to make is this if a jacketed bullet has less friction resistance in its passage through a barrel why then do we not use jacketed bullets to slug our barrels?

[quilbilly]

Since a cast lead lubed boolit of the same weight of a jacketed boolit with the same powder charge generally reaches a higher muzzle velocity (often 150 to 250 fps.)… At least that is what I have found on my home range and chronograph. Depends on the lube I guess.

[cbrick]

I can't believe that Western Powders thinks there's lead in a pencil? :veryconfu

It says it's a blog, did Western Powders make that statement or someone with their head screwed on backwards.

102410

Old wives tales will never die.

Rick

[waksupi]

That's just silly.

[MtGun44]

BULLhocky.

Why do you think that all plain journal bearings like in every car out there are lined with LEAD alloy?
Because it has extremely low coefficient of friction on smooth steel when properly lubricated. Lower
than anything else or they would be using the "anything else".

Bill

[waco]

This belongs in the "silliest things you've heard" thread a few lines down. :)

[swheeler]

I think they got it bassakwards;)

[Bullshop]

Maybe someone should tell them.

[fredj338]

Here is an interesting tidbit...I would have assumed the opposite.

Here is a quote off the Western Powders blog from their ballistics labs:


http://blog.westernpowders.com/2014/04/dear-labby-questions-customers-ask-our-ballistics-lab/

Lead Bullet Pressure

Actually it is a general question: All things being equal do lead bullets generate more pressure than jacketed bullets?

Yes, they do. It all comes down to the frictional co-efficient. Gilding metals like copper slide more readily than lead does on a steel surface. You can write your name on a piece of paper using a lead bullet much more readily than you can with a copper one. This tendency to smear, which is why it leaves a track on paper is also why it tends to grab the barrel more quickly and increase pressures. Using jacketed bullet data with a lead bullet of the same weight will result in higher pressures, everything else being equal.
I have always felt this way about lead bullets. The size, better pressure seal, & higher friction raise pressures. Not a lot, but a bit higher than equiv jacketed loads. I don't believe lead in fuels is the same as pushing a lead bullet down a bbl. Until I can get a Pressure Trace setup to prove or disprove it, that is my story.

[osteodoc08]

Sometime I just have to SMFH

[RPRNY]

There's a gentleman who posted above who has pressure test equipment and has done a good deal of pressure testing with cast and jacketed. He's not speculating when he signals his disagreement with the premise.

[williamwaco]

That is another case of an "expert" mouthing off about lead bullets.


Lyman 49.

.30-30

170 grain jacketed
3031 28.5 gr 36,900 CUP


170 gr Cast
3031 28.5 gr 32,500 CUP


Examples are not easy to find but if you look there are plenty of them in there.

I have never seen a case where the cast bullet produced higher pressure than jacketed.

[williamwaco]

I may well be wrong and it wouldn't be the first time. If leaving a lead smear on paper shows it has a higher coefficient of friction, then the graphite in a pencil must really be high! Also try pushing a jacketed bullet through a barrel and compare that to a lead one.


Touche'

[hickfu]

I read this while lubing some boolits so I grabbed my reloading manual (Lyman 49th) and picked a caliber I reload for... 45-70

500gr Jacketed bullet: 49gr H322 = 1673fps 36,5000 CUP
500gr lead boolit: 51gr H322 = 1753fps 36,7000 CUP

Seems to me that if I used 49gr of H322 on the Lead boolit it would have a lot less pressure.
46gr of H322 = 24,700 CUP

Doc

[deltaenterprizes]

The pressures listed in the LEE Reloading Manual for 40 S&W with a 180 TC boolit & bullet show much lower pressure for the lead boolit.

[dragon813gt]

So the shot start initiation pressures that QuickLoad uses are backwards. Good to know and I will adjust the program accordingly.

[rking22]

well, now I have NO confidence in anything from Western Powders! Didn't know they sold bullets ,so can only assume they didn't bother to actually use that fancy test equipment to determine their answer , just took a swag and threw in some teck terms to support their guess. Think someone should request an actual pressure trace for 2 170 gr 30 cals in a 30WCF , Wonder if hey would do the test?

[DeanWinchester]

Heck, I'm dummer than a bag of hammers but I have chrono'd equal weight bullet/boolit [9mm] with the same powder charge and ALWAYS got lower velocity from the cast boolit. I was laboring under the delusion that low velocity and low pressure kinda held hands every once in a while.

[Grump]

I beg to differ on the thought that this is a *universal* effect.

I did book-lernin' research like 20 years ago when .40 S&W kB! events were popping up in Glocks shooting lead bullets, and actually collected an eyewitness account of one going to case failure and shattering the grip while inflating the magazine and dumping the unfired rounds on the ground. Report was it had gone about 700 rounds of lead without cleaning...

Anyway, Winchester's manual back then showed lower charge weights with similar velocities and pressures with lead bullets compared to jacketed of same weight--most of the time. Differences AFAIRemember were anywhere from zero to 7% less charge weight for the lead loads.

This was across several calibers, though I was paying the most attention to .40 S&W, 9mm and .357 Mag at that time.

My own experiences tend to bear this out, at least at higher pressures. Jacketed and plated 125s in the .357 tend to burn the powder the same, but Oregon Trail 125s at BHN 22, and some of our own cast ones at BHN 14-16, showed flatter primers and a bit more velocity than the others. This was with Win 296, Alliant Power Pistol, and maybe with Win 231. Might have even seen it with Unique or Herco, but I don't remember for sure and the notes are where I don't want to go right now.

All three bullet types had pretty much the same bearing surface and were all loaded to the same OAL/intrusion into the powder cavity.

With so many citations to published rifle caliber data and personal rifle experiences, I wonder if the effects I observed are reversed with somewhere more than 7-10 inches of barrel being involved, as far as velocities effects go. Chamber pressure drops so fast I would expect there to be no differences between rifles and pistols using the same cartridge.

[44man]

Might make a good "sticky in the funny department!"

[DeanWinchester]

There is a good side to BS like this. It scares away the sheeple. Leaving the lead for the rest of us.

[fredj338]

Heck, I'm dummer than a bag of hammers but I have chrono'd equal weight bullet/boolit [9mm] with the same powder charge and ALWAYS got lower velocity from the cast boolit. I was laboring under the delusion that low velocity and low pressure kinda held hands every once in a while.
Exact opp for me. With any handgun caliber, any powder, I always get higher vel with lead bullets with equal charge wts. Since there is no free lunch, all things being equal, higher vel = higher pressures. The idea a lead bullet offers less friction would be the opp in pressures. Look at any data, or check your own, slippery bullets, like moly, need higher charge rates to get sim vel as non coated???

[waksupi]

Cast are slicker than jacketed, so produce more velocity with less pressure.

[DeanWinchester]

Hmmm, I'll go dig out my load book and see what I wrote down.
I know it was AA#5 with a 124g FMJ and a 125g Lee RN. I'm right certain velocity with the cast was lower but it's not like it'd be the first brain fart I ever had.

[DeanWinchester]

Alright. Let this be a lesson to myself and everyone. Meticulous record keeping is pretty important. ;-)
I've got wrote down that a 124g FMJ in Win case and 5.5g of AA#5 averaged 1060FPS and 125g Lee [same case, charge and primer] averaged 960fps. My lyman manual begs to differ. OBVIOUSLY, I wrote it down assbackwards.....but I distinctly remember remarking to guys at the range that it seemed strange and jotted it down in my book as such.

Does this win me the idiot of the day award?

[Bullshop]

Hand gun rounds are going to be effected by the depth of the base of the bullet in the case there by effecting the case volume. Many cast boolit designs will have the base of a seated boolit farther out or up the case than a jacketed bullet of the same weight. In small volume cases this will have a very significant effect on pressure. Same case, projectile weight, powder and charge, primer, but different internal volume for the different projectile types. Rifle rounds will not to any significant degree be effected by such a difference in seating depth.
In my experience I am sticking with my first assertion but specifically referring to rifle rounds with at least mid size volume like a 308.

[Whitespider]

I'm gonna' call everyone of ya' on this...
Higher pressure equals higher velocity only if all else remains equal... change projectiles, even of the same weight, and all bets are off.
Comparing cast to jacketed, based only on weight, is not possible.
Y'all should go to the Hornady reloading center and play around some... there ain't no set "rule" relating to pressure, velocity, or anything else.
Here's some examples from the website...

.38 Special
125 gr. HDY XTP - 6.0 grs. SR4756 - 1046 fps - 16,400 psi
125 gr. cast swc - 6.0 grs. SR4756 - 1091 fps - 16,100 psi (same powder, higher velocity, lower pressure)

125 gr. HDY XTP - 6.3 grs. CFE - 1133 fps - 16,000 psi
125 gr. cast swc - 6.2 grs. CFE - 1201 fps - 16,100 psi (less powder, higher velocity, higher pressure)

125 gr. HDY XTP - 6.2 grs. AutoComp - 1068 fps - 16,500 psi
125 gr. cast swc - 6.2 grs. AutoComp - 1139 fps - 10,800 psi (same powder, higher velocity, lower pressure)

158 gr. HDY XTP - 10.0 grs. H4227 - 864 fps - 15,500 cup
158 gr. cast swc - 10.0 grs. H4227 - 983 fps - 15,700 cup (same powder, higher velocity, higher pressure)


.44 Magnum
240 gr. Nosl JHP - 10.0 grs. Tightgroup - 1292 fps – 37,700 cup
240 gr. cast swc - 10.0 grs. Tightgroup - 1288 fps – 38,400 cup (same powder, lower velocity, higher pressure)

240 gr. Nosl JHP - 11.0 grs. HP38 - 1272 fps – 37,800 cup
240 gr. cast swc - 11.0 grs. HP38 - 1288 fps – 38,400 cup (same powder, higher velocity, higher pressure)

240 gr. Nosl JHP - 10.2 grs. Universal - 1246 fps – 38,200 cup
240 gr. cast swc - 10.2 grs. Universal - 1276 fps – 37,500 cup (same powder, higher velocity, lower pressure)

[JonB_in_Glencoe]

All things CAN'T be equal !

It's kinda like saying this...All things being equal, If a ship and a train have the same size engine, A train can haul more freight than a Ship, because the water creates more friction against the steel hull of the ship, than the train's steel wheels on steel rails.

[Bullshop]

On the examples you have given there is no indication as to where the bullet base is. To be an equal comparison with hand gun rounds the case volume has to be equal. If one is deeper seated than the other that in itself will effect the pressure.
In order to have an apples to apples comparison it is critical that the bullet bases be seated to the same depth in the case or all bets are off.

[Whitespider]

...try pushing a jacketed bullet through a barrel and compare that to a lead one.

Lead does have a higher frictional co-efficient than copper... but copper resists deformation more than lead.
If you don't believe lead has a higher frictional co-efficient try this simple test...
Take a pair of lead ingots of the same size, glue a piece of sheet copper on one flat of one ingot, place them on a piece of plate steel (copper down)... now slowly raise one edge of the plate and see which ingot slides off first.

You can't push a bullet made of ice down the bore either... would you say ice has a higher frictional co-efficient than lead??

[Whitespider]

All things CAN'T be equal !

I didn't say "all things", I said "all else".
In other words, the same bullet will gain velocity if pressure is increased (by increasing the powder charge)... but the same can't be said if two different bullets are used. You can't expect two bullets of same weight but different construction (construction may mean material, shape, bearing surface, or any number of other things) to achieve identical velocities just because pressure is identical... one or the other is likely to go considerably faster.

Pressure is only relative to the same bullet... not two different bullets.

[MtGun44]

NO - lead does NOT have a higher coefficient of friction than copper when lubricated against smooth steel, it is lower. This is why the bearings inside your engine in your car have LEAD ALLOY on the surface.

Bill

[Whitespider]

NO - lead does NOT have a higher coefficient of friction than copper when lubricated against smooth steel, it is lower. This is why the bearings inside your engine in your car have LEAD ALLOY on the surface.

Better check your facts.
Typically the babbitt material covering main and rod bearings contains less than ½% lead (like o.3 or o.4%).
They are a tin based alloy and contain more copper and/or antimony than lead. They work because of a "pressurized" lubricating system that "floats" the crank journals within them. The reason for the "soft(ish)" layered alloys is not for their "slipperiness"... rather so it doesn't destroy the crank when the bearing fails.

[WallyM3]

Are we talking static or kinetic coefficients of friction?

[JonB_in_Glencoe]

I didn't say "all things", I said "all else".
In other words, the same bullet will gain velocity if pressure is increased (by increasing the powder charge)... but the same can't be said if two different bullets are used. You can't expect two bullets of same weight but different construction (construction may mean material, shape, bearing surface, or any number of other things) to achieve identical velocities just because pressure is identical... one or the other is likely to go considerably faster.

Pressure is only relative to the same bullet... not two different bullets.
I was referring to the OP

[rking22]

Rereading that posting several times , all things are not equal ! We "hardly ever" shoot an unlubricated lead bullet and we "hardly ever" shoot a lubricated J word. Also a cast bullet with those loob groves or TL rings has signifigantly less bearing surface than a same weight copper clad bullet. The force required to engrave the rifling is reater with the jacketed due to this bearing surface difference as well as a generally "harder" jacket to deform. This all happening just as the bullet starts to move. Case volume determined by seating depth makes it near impossiable to compare from load data in manuals without measuring the compared bullet lengths . Oh well , I agree, more lead for us is a good thing. Scare em all away!

[MtGun44]

The journal bearing has two modes - as the engine just starts you have sliding friction as the bearing
surface is directly in contact with the steel journal, with a bit of oil. As the speed builds up, the oil
film is pumped in and the bearing actually lifts off the surface on a few thousandths of oil film and
never again touches the journal until shutdown as the rotational speed drops below the liftoff speed.
Zero wear when running, only at startup and shutdown.

Boolits are like the bearing prior to liftoff - metal to metal lubricated contact, but not static.

Bill

[hermans]

I would like to get a little more than a shake of the head from Gear....this is what makes this the best forum ever!!! Keep it up guys!!!

[Whitespider]

I was referring to the OP

Oh... my bad for jumping on it... my apologies.

[beagle]

Interesting thread but bunk IMO. We are assuming everything is equal here. Now, a jacketed and cast bullet will never be the same. We might try to get them identical but it can't be done. Another variable we're not considering is the diameter. Ever try shooting a .308" diameter cast bullet in a .30/30? I'm betting the jacketed will have a higher pressure with the excess freebore by shooting an "undersize" (to us cast shooters who normally use .310s or .311s) cast bullet. We'll also probably have bad accuracy and leading as a bonus plus less velocity./beagle

[mold maker]

Another NONE equal exist in the grip of the brass crimp on the soft lead (with lube), and the harder surface of jacketed.
The pressure needed to break the bond is less with cast. Thus the movement of the boolit is sooner, increasing the gas pressure space, and giving the boolit a head start.
If the boolit is soft enough to obdurate it does so as it clears the case mouth sealing it's self to the throat.
The case with jacketed is a tightener bond with the jacket and the case, and a slower initial movement, meaning higher pressure to begin with.
I know this just muddies the water, but has to be addressed in the total discussion.

[WallyM3]

"Boolits are like the bearing prior to liftoff - metal to metal lubricated contact, but not static.

Bill"

This is what I was envisioning for lubed lead. In the case of copper jackets, the coefficient would initially be considered static (against brass), then dynamic (against steel).

The effects of the different lubrication might be slightly different, but probably way too small to influence calc. of µ.

Too many variables to contemplate in building a model that might produce meaningful result. Still, it's fun generalizing.

I worked with 4 bearings that were 18.25" in diameter. We had to artificially begin their rotation well ahead of being turned by the prime mover (35,000 hp steam turbine) in order to ensure that there was an oil film between the steel and the babbitt metal (in one bearing's case, lignum vitae and water).

[Marlin Junky]

...Yes, they do. It all comes down to the frictional co-efficient. Gilding metals like copper slide more readily than lead does on a steel surface. You can write your name on a piece of paper using a lead bullet much more readily than you can with a copper one. This tendency to smear, which is why it leaves a track on paper is also why it tends to grab the barrel more quickly and increase pressures. Using jacketed bullet data with a lead bullet of the same weight will result in higher pressures, everything else being equal.

That is one of the most pathetic explanations I've ever heard... problem is, lots of beginners will believe it.

The real answer lies in real physics.

Obturate a soft bullet (boolit) to the point where you have excessive force vectors normal to the axis of the bore vs. parallel to the axis of the bore and pressure behind the "obstruction" (the boolit) will escalate.

MJ

P.S. it has nothing to do with the coefficient of friction of Pb vs. Cu as given enough obturation of either material, their "COF's" will skyrocket to the point of becoming obstructions... BOOM!

[Digital Dan]

I have to smile a wee bit about this thread. There was just recently a similar thread at 24hr Campfire espousing what the OP in this thread said. It was largely supported by the jacketed bullet crowd in all the same fashion, load book and Oehler PBL reference, etc. etc.

If you all want to put a symposium together to debate this I'll bring the popcorn.

[BAGTIC]

All things CAN'T be equal !

It's kinda like saying this...All things being equal, If a ship and a train have the same size engine, A train can haul more freight than a Ship, because the water creates more friction against the steel hull of the ship, than the train's steel wheels on steel rails.


NO WAY. Ship can always haul more with same horsepower. For one thing ships always work on the level and don't need extra h.p. for hill climbing. Trains haul it faster but at the speed ranges where most ships operate trains can not come anyways near the ton/miles performance of a ship.

[JonB_in_Glencoe]

Bagtic,
I'm glad you agree with me that "all things can't be equal" :bigsmyl2:

[BAGTIC]

Whether a cast produces higher or lower velocities can vary according to particular powder charge can depend on the particular bullet weight and resistance. If given bullet weight is combined with a powder a little to slow to be optimal a higher resistance bullet is can raise pressures and combustion efficiencies thereby increasing velocity. If a max load using a resistance bullet has a lower resistance bullet substituted the lower pressures generated will produce lower velocities until the powder change is increased to increase pressure.

Even if the bullet seating depth is the same it does not mean that travel distance to contact with the lands will be the same due to different bullet OAL and ogive shapes.

Also a softer bullet may expand more in the throat and the need to be swaged down more at the leade while a harder bullet may expand little.

Military tests have showed that military FMJ .308 bullets using dead soft lead cores raised pressures compared to the same bullet with harder lead cores due to the softer cores actually expanding bullet diameter due to high chamber pressures.

There is no single solution or explanation.

[gtgeorge]

Wow what an interesting debate. I can only see this being settled for sure with someone with pressure testing equipment since so many ways to look at things. One can look at how hard it is to push two same weight bullets with equal bearing surface through the bore but then have to wonder how that compares to under pressure with how the bullet may swell, the heat involved and what happens with the lube etc. when being fired. It would require finding 2 bullets of the same weight, bearing surface and seated to the same depth in identical case volumes and a pressure measurement taken.

Since without all this being available I will also add my WAQ to this in that I believe the lead develops more pressure since I think it seals the combustion chambers better from start to finish. I do think it will move easier down the bore as it progresses due to the lube coming into play but do not know how pressures actually build. Isn't the highest pressure very early on in the combustion process?

But then on the other hand when I compare loads I have worked up in a 400 CB with similar weight lead and copper, I am able to add more powder and get more velocity before showing pressure signs on hot loads with lead. Once again a non scientific guess.

It would be really nice if someone with test equipment could and would do some side by side testing to determine the true answer. I wonder if Western powders did indeed base that info on actually testing taking into consideration all the aspects involved?

[Whitespider]

There is no single solution or explanation.

And that there says it all‼

[Super Sneaky Steve]

Some other factors to think about.

Our cast boolits are often a little over sized. If an oversized jacketed bullet were used what would that do to pressure?

Second, after whacking thousands of jacketed boolits with a hammer I can say they aren't all the same hardness. Both jacketed and cast boolits have different degrees of hardness. Comparing a very hard cast boolit to a soft jacketed boolit doesn't seem fair. I'd like to see a test where the cast boolit is the same hardness as the core of the jacketed boolit.

[steve4102]

All things being equal a Lead bullet will generate HIGHER pressure that a Jacketd Bullet with identical powder charges.

Western Powders is not the only ones who have published this.

Lyman 48 page 99 says,
A soft bullet may cause higher pressure because the bullet is so malleable that the sides will push hard against the bore when high pressure is exerted on the base.

Handloader Magazine says,
Normally a lead bullet of the correct diameter and hardness produces more pressure with the same powder charge, because it does seal the bore better.

Hodgdon's web site,

.44 Magnum handgun--
240 cast/ 22.0 IMR4227/ 33,300 CUP
240 jacketed/ 22.0 IMR4227/ 28,400 CUP

.38-55 rifle--
250 cast/ 27.0 H322/ 27,000 CUP
255 jacketed/ 27.0 H322/ 25,500 CUP

250 cast/ 24.0 IMR498/ 36,200 CUP
255 jacketed/ 24.0 IMR4198/ 31,400 CUP

Please not that even though the jacketed bullet in the .38-55 weighs 5 grains more, pressures are less with the same powders charges. And in all the above instances, the STARTING load with jacketed bullets is the MAX load with cast bullets.

Take a look at Hornady #7 45 ACP data for example.

230gr FMJ COL = 1.230. This bullet measures .651 inches.

230gr Lead RN = 1.245. This bullet measures .640 inches.

So the Jacketed bullet is .011 longer and is seated .015 deeper, for a total of .026 deeper.

Data.
N-340 Lead, Max = 6.6gr. Jacketed. Max = 6.7gr.
Even with the .026 deeper the jacked bullet used more powder.

Clays Lead, Max = 6.2gr. Jacketed. Max = 6.4gr
Even with the .026 deeper the jacketed used more powder.

231 Lead, Max = 6.2gr. Jacketed. Max = 5.7gr
Here the Lead bullet with less seating depth used more powder. Maybe due to COL, maybe due to the lead bullet.

Unique Lead, Max = 6.3gr. Jacketed. Max = 6.1gr
Again we have more powder with lead than we do with Jacketed.

We can also look at Speer #13. They list their 230gr L-RN at 1.270 COL and their Jacketed 230gr TMJ at 1.260. I do not have the length of the L-RN compared to the TMJ, but of the five(5) powders that are used for both the Lead bullet used significantly less powder than the Jacketed TMJ.

All we have to go on as handloader is load data. Theories are great and often times helpful, but when they conflict with actual pressure tested data, it's best to follow the data and no the "Theory".

So far I have seen no evidence here that Lead bullets build less pressure than jacketed.

[RPRNY]

I am firmly in the all other things being equal, a jacketed bullet will deliver high pressures than a lead bullet camp but am prepared to listen.

If boolit pressures are higher, why are faster powders generally used for the same weight cast vs jacketed? Is this only to achieve the lower velocities that cast favor or because less resistance requires a faster powder?

[Uncle R.]

Veral says cast boolits give less pressure.
My experience agrees with Veral but I can only judge pressure from things like primer appearance, case head appearance and case expansion. Obviously I can get no closer than a SWAG but keeping in mind the less than certain nature of my results I'll still say my experience agrees with Veral.
<
There is a proviso that I've very seldom used extremely soft boolits - in fact for many years before I found this place I used boolits that were harder than optimum. Those hard boolits almost always gave higher velocity than jacketed (verified by chronograph) with equal charges, and if there was a pressure difference large enough to note by my SWAG methods the boolits gave less pressure. For many years and in dozens of different loads I have routinely swapped my linotype hard gas-checked boolits in magnum handgun jacketed recipes and never had a problem.
<
Just my experience. Even so I wouldn't be too surprised to see very soft boolits or heavily leaded bores give higher pressures than jacketed.
<
Uncle R.

[Camba]

"...Another point I would like to make is this if a jacketed bullet has less friction resistance in its passage through a barrel why then do we not use jacketed bullets to slug our barrels? ..."

The above statement is a great clue.

I am wondering it the Western Powders post was dated 4/1/14.
:)

[62chevy]

"...Another point I would like to make is this if a jacketed bullet has less friction resistance in its passage through a barrel why then do we not use jacketed bullets to slug our barrels? ..."

The above statement is a great clue.

I am wondering it the Western Powders post was dated 4/1/14.
:)

Not buying that about slugging a barrel. Pure lead is softer than pure copper and lead forms easier to the barrel.

[steve4102]

Jacketed bullet are also to hard to seal the bore completely. This causes gasses (pressure) to escape past the bullet wasting energy and reducing pressure. Kinda like worn out rings on your pistons.

Check you manuals, really check them.

You will find hundreds of examples were the jacketed bullets required More powder to achieve the same pressures as the lead bullets. You will also find hundreds of examples where Lead bullets generated more pressure than jacketed bullets with the same or less powder.

Western Powders is correct, as is Lyman, Handloader Magazine and Hornady.

[PAT303]

I think the above post makes sense. Pat

[Mik]

http://m.youtube.com/watch?v=C2aQpVKiCN8

Interesting video that makes me wonder if hard cast bullets really do conform to the bore more readily than jacketed bullets.

[dh2]

I am still learning about this bullet casting but if this is true why due we not slug the bore with a jacketed bullet?

[Mik]

I am still learning about this bullet casting but if this is true why due we not slug the bore with a jacketed bullet?

I don't know.

Maybe because lead is less resistant to shearing forces than copper? I've only slugged a few bores but I always have a ring of lead left at the muzzle that was sheared off when I tapped the slug into the bore. I don't see this happening with copper.

In my head, this is what allows a jacketed bullet to be pushed harder than a pb lead bullet. The copper jacket offers more resistance to the shearing forces applied by the rifling. It's also my theory as to the reason you can get away with firing undersized jacketed bullets. You don't need as much material to engage the rifling because the jacket is more resistant to shearing. With a lead bullet, you need to fill those grooves, not necessarily to prevent gas escape, but to keep the bullet from "pushing" past the rifling.

All theories and guesses. Not based on science, knowledge, or experience! Someone please correct me if I'm on another planet.

[Whitespider]

I am still learning about this bullet casting but if this is true why due we not slug the bore with a jacketed bullet?

That's been brought-up three or four times in this thread...
Jacketed bullets wouldn't work for slugging the bore... but not because of friction.

For one thing, copper is "harder" than lead and would "spring back" so we wouldn't get anything close to an accurate measurement. But a jacketed bullet isn't that difficult to drive through a barrel, I've had a squib load stick a copper-condom bullet in the bore more than once and they ain't anymore difficult to drive out than a cast. We use soft lead (not hard-cast) to slug a bole because it's malleable, it easily conforms to the shape (like putty would) and doesn't spring back when it exits... we don't use it because it's because it's slippery. Don't confuse "friction" with "malleability"... they ain't the same.

Listen, I ain't defending what Western Powders has stated on their website... there's plenty of evidence, such as some load data, indicating it ain't so. But at the same time there's plenty of evidence, such as some load data, indicating it is. I just don't believe it's as simple as that... I don't believe you can say "always". I have personal (observational, non-scientific) experience of it being both ways depending on gun, load, projectile, and whatnot. But using comparisons to "bore slugging", "engine bearings", and other such don't work... they ain't the same dynamics as a projectile being forced down the barrel under pressure.

[rhead]

Someone would have to make a mould cavity that would cast an exact copy of a jacketed bullet. Then pressure test enough of them to rule out random variations. then the data would be valid for that boolit and that load.

Start decreasing the loads and fire them. which projectile will stick first? The friction is also dependent on speed.

[steve4102]

Listen, I ain't defending what Western Powders has stated on their website... there's plenty of evidence, such as some load data, indicating it ain't so. But at the same time there's plenty of evidence, such as some load data, indicating it is. I just don't believe it's as simple as that... I don't believe you can say "always".

Don't forget, Western Powders are the ones with Millions of Dollars worth of pressure testing Equipment, while most of the people claiming Western is full of ****, have a loading press, a PC and an Opinion. Not much of a comparison if you ask me.

[steve4102]

Someone would have to make a mould cavity that would cast an exact copy of a jacketed bullet. Then pressure test enough of them to rule out random variations. then the data would be valid for that boolit and that load.

Start decreasing the loads and fire them. which projectile will stick first? The friction is also dependent on speed.

Ya mean like Hornady data found here.

Take a look at Hornady #7 45 ACP data for example.

230gr FMJ COL = 1.230. This bullet measures .651 inches.

230gr Lead RN = 1.245. This bullet measures .640 inches.

So the Jacketed bullet is .011 longer and is seated .015 deeper, for a total of .026 deeper.

Data.
N-340 Lead, Max = 6.6gr. Jacketed. Max = 6.7gr.
Even with the .026 deeper the jacked bullet used more powder.

Clays Lead, Max = 6.2gr. Jacketed. Max = 6.4gr
Even with the .026 deeper the jacketed used more powder.

231 Lead, Max = 6.2gr. Jacketed. Max = 5.7gr
Here the Lead bullet with less seating depth used more powder. Maybe due to COL, maybe due to the lead bullet.

Unique Lead, Max = 6.3gr. Jacketed. Max = 6.1gr
Again we have more powder with lead than we do with Jacketed.

[JSnover]

Western apparently hasn't read anyone else's manuals...

[Bullshop]

I cant help thinking about the fact the a guilding metal jacket without lube or for that matter a cartridge case without pushed into a die will act quite differently than a lead bullet pushed into a die without lube.
Anyone ever have a stuck case in a sizing die from not using enough lube? Bet ya wont do that again! How about a jacketed bullet in a swage die with insufficient lube? Bet ya wont do that again. Consider that you can push a lead billet into a squirt die and swage it to a larger diameter to the point that excess metal is squirted out a little vent hole but still the swaged lead billet will push easily from the die without lube.
That being said which has the greater friction?
Considering that all our lead and lead alloy boolits are lubed and none of our jacketed bullets are lubed which one would seem to offer the greater resistance in its passage through a barrel?
The guilding metal jacket is harder so harder to initially deform or displace metal to the rifling but that is only for the length of the bearing surface initial entry into the lands. Once it has passed that far the deforming is over and what is left is friction.
I don't understand how say at 40,000 psi one typ can exert more pressure against the barrel wall than the other. Neither can exceed the chamber pressure and once the pressure is sufficient to obturate either type the the outward pressure of the bullet sides to the barrel should be the same.
I have seen .451" jacketed pistol bullets fired in a 45 cal ML where the bullet was small enough to slide down the barrel without engraving fired with black powder and the recovered bullets were fully engrave by the rifling and by the way produce excellent accuracy. By this it would seem that there is not all that much difference in the pressure required to obturate a jacketed bullet over a cast.
I have no theories, or pressure data or scientific anything these are just things I have observed that lead me to my conclusions.

[steve4102]

Western apparently hasn't read anyone else's manuals...
Ya mean like Lyman, that says this:
Lyman 48 page 99 says,
A soft bullet may cause higher pressure because the bullet is so malleable that the sides will push hard against the bore when high pressure is exerted on the base.


...and Hornady that says this:

230gr FMJ COL = 1.230. This bullet measures .651 inches.

230gr Lead RN = 1.245. This bullet measures .640 inches.

So the Jacketed bullet is .011 longer and is seated .015 deeper, for a total of .026 deeper.

Data.
N-340 Lead, Max = 6.6gr. Jacketed. Max = 6.7gr.
Even with the .026 deeper the jacked bullet used more powder.

Clays Lead, Max = 6.2gr. Jacketed. Max = 6.4gr
Even with the .026 deeper the jacketed used more powder.

231 Lead, Max = 6.2gr. Jacketed. Max = 5.7gr
Here the Lead bullet with less seating depth used more powder. Maybe due to COL, maybe due to the lead bullet.

Unique Lead, Max = 6.3gr. Jacketed. Max = 6.1gr
Again we have more powder with lead than we do with Jacketed.

...and Hodgdon says this.

.44 Magnum handgun--
240 cast/ 22.0 IMR4227/ 33,300 CUP
240 jacketed/ 22.0 IMR4227/ 28,400 CUP

.38-55 rifle--
250 cast/ 27.0 H322/ 27,000 CUP
255 jacketed/ 27.0 H322/ 25,500 CUP

250 cast/ 24.0 IMR498/ 36,200 CUP
255 jacketed/ 24.0 IMR4198/ 31,400 CUP

Please not that even though the jacketed bullet in the .38-55 weighs 5 grains more, pressures are less with the same powders charges. And in all the above instances, the STARTING load with jacketed bullets is the MAX load with cast bullets.

And THIS!


Jacketed IMR SR 4756 .451" 1.200" 6.4 762 12,900 CUP 7.0 867 16,500 CUP

Lead,IMR SR 4756 .452" 1.200" 6.3 813 14,200 CUP 6.8 892 16,400 CUP




Hodgdon Jacketed HS-6 .451" 1.200" 8.0 790 14,400 CUP 8.2 825 15,400 CUP

Hodgdon Lead HS-6 .452" 1.200'' 7.0 751 12,900 CUP 8.0 859 16,600 CUP




Hodgdon Jacketed, CFE Pistol .451" 1.200" 6.0 815 16,000 PSI 6.8 934 19,800 PSI

Hodgdon Lead, CFE Pistol .452" 1.200" 5.4 816 14,600 PSI 6.2 942 20,100 PSI


Hodgdon Jacketed, Universal .451" 1.200" 5.1 716 11,800 CUP 5.6 844 16,800 CUP

Hodgdon Lead, Universal .452" 1.200" 4.5 703 11,400 CUP 5.4 857 16,800 CUP




Winchester Jacketd, WSF .451" 1.200" 5.7 766 12,100 CUP 6.4 851 15,700 CUP

Winchester Lead, WSF .452" 1.200" 5.8 832 14,500 CUP 6.3 892 16,800 CUP


Winchester Jacketed WST .451" 1.200" 4.1 733 13,900 CUP 4.9 848 16,100 CUP

Winchester Lead, WST .452" 1.200" 4.0 776 14,300 CUP 4.3 812 16,400 CUP

I would suggest that those that disagree with Western Powders should take the time to Read Their manuals as well.

It would appear that those that disagree with Western would have to disagree with Hodgdon, Lyman, Hornady, Speer and just about every other $$Ballistics$$ lab that supplies us with usable data.

Read your manuals, really read them.

[Bullshop]

I think there are other factors involved other than just the one we are looking at. I do read those manuals and much of what I have read has been proven wrong. Just because they say so does not necessarily mean it is so.
Just as every gun is a law unto itself so too is everybody's loading conditions somewhat different than everyone else's.
How about this, will a 44 mag loaded with 10gn Unique and a boolit cast from pure lead have more pressure that the same 44 mag firing the same charge of Unique under a boolit cast in the same mold but of COWW and will the COWW load have higher pressure than the same charge of Unique loaded under a boolit cast from the same mold but using linotype? If what they are saying in the book that because lead is softer than a jacket the pressure is higher then it would have to follow through the same because each example of cast boolits given is progressively harder than the previous.
This is a much better comparison to prove a theory because everything is the same accept the alloy.

[RobS]

Nothing is equal here since both jacketed and cast bullets/boolits are entirely different from one another. One also needs to examine the hardness of a cast boolit too and if it has a gas check sitting on its ars end. Looking at the online Hodgdon data one can see in the 454 Casull section a 325 grain jacketed soft point has more pressures and a bit faster velocity vs a 335 grain Cast Performance hard cast (18-21BHN) boolit with a GC. Again bullet/boolit length is not known but the heavier Cast Performance boolit is seated to a shorter OAL as well. It doesn't matter if it's 4227, H110, or LilGun the hard cast boolit shows less pressure and less velocity for the same starting/minimum charge weight in powder. More interesting is the results in the Cast Performance hard cast 325 grain plain base bullet that is nearly the same loaded OAL as the 325 grain jacketed soft point.

Check it out www.hodgdon.com

http://i612.photobucket.com/albums/tt206/RobS01/Hodgdon454Casulldata_zps2d517987.jpg (http://s612.photobucket.com/user/RobS01/media/Hodgdon454Casulldata_zps2d517987.jpg.html)

Also similar info on the hodgon site above for the Ruger/TC/Freedom Arms 45 Colt load data as well between those same two 325 grain bullets/boolits that was used in the 454 Casull data.

As we talk about the deformation/obturation of a cast boolit are we discussing a swage boolit or??????BHN????? None the less the discussion here will be supported both ways as there are variables to cast boolits.


Looks like as I was typing Bullshop just above was getting to what I wrote regards to difference in boolit hardness.

[JSnover]

Ya mean like Lyman, that says this:
Lyman 48 page 99 says,
[I]A soft bullet may cause higher pressure because the bullet is so malleable that the sides will push hard against the bore, [etc. etc, etc]...

...
Please not that even though the jacketed bullet in the .38-55 weighs 5 grains more, pressures are less with the same powders charges. And in all the above instances,…

I would suggest that those that disagree with Western Powders should take the time to Read Their manuals as well.

It would appear that those that disagree with Western would have to disagree with Hodgdon, Lyman, Hornady, Speer and just about every other $$Ballistics$$ lab that supplies us with usable data.

Read your manuals, really read them.

I did read the manual and I disagree with Western.
Lyman 48th had this to say on page 137:

222 Remington

55 grain JSP
Powder Max Load Velocity Pressure (CUP)
748 24.2 2885 44,200

55 grain #225415 (#2 alloy)
Powder Max Load Velocity Pressure (CUP)
748 25.0 2881 25,000

And on page 211:

30-30 Winchester

170 grain JFP
WLR primer
Powder Max Load Velocity Pressure (CUP)
IMR3031 28.5 2054 36,900

#311291 (#2 alloy)
CCI200 Primer
Powder Max Load Velocity Pressure (CUP)
IMR3031 28.5 2095 32,500

The list goes on but the correct answer is it depends.
It only took me a few minutes to find two examples of virtually identical loads with 4,000 to 19,000 CUP between them and the lead boolit is the lower of the two. Western's mistake was to make a blanket statement. They should know better.
Read your manuals.

[steve4102]

I did read the manual and I disagree with Western.
Lyman 48th had this to say on page 137:

222 Remington

55 grain JSP
Powder Max Load Velocity Pressure (CUP)
748 24.2 2885 44,200

55 grain #225415 (#2 alloy)
Powder Max Load Velocity Pressure (CUP)
748 25.0 2881 25,000

And on page 211:

30-30 Winchester

170 grain JFP
WLR primer
Powder Max Load Velocity Pressure (CUP)
IMR3031 28.5 2054 36,900

#311291 (#2 alloy)
CCI200 Primer
Powder Max Load Velocity Pressure (CUP)
IMR3031 28.5 2095 32,500

The list goes on but the correct answer is it depends.
It only took me a few minutes to find two examples of virtually identical loads with 4,000 to 19,000 CUP between them and the lead boolit is the lower of the two. Western's mistake was to make a blanket statement. They should know better.
Read your manuals.

Ah, but you are again forgetting, Western Powders has Millions of dollars invested in pressure barrels and pressure testing equipment and thousands of hours and pages of Actual Data. You have a PC, a Manual or two and an Opinion.

Their load data falls on both sides of the fence as does Hornady, Lyman, Hodgdon and Alliant. This is a fact and cannot be denied, agreed.

Western powders put the jacketed vs Lead into generic perspective, "All things being equal" based on their actual Pressure lab tests and came up with the same results as Lyman, Hodgdon, Hornady and Handloader Magazine.

When you getcha some Pressure Trace Software and test Lead vs Jacketed for yourself, post your results here. Until then I'll put my faith in those that have the $$ Equipment$$ and the Knowledge to determine Pressures and not with an internet opinion.

Carry on gentlemen.

[steve4102]

Here is a comment from a Handloader that has a Pressure testing system not just an opinion and a PC.

In every test I run with a pressure gun (piezo sensor), with the same powder load lead bullets gave higher pressures respect to jacketed ones; and with the same pressure, lead bullets gave higher speeds.

Link, Post #8

http://forums.1911forum.com/showthread.php?t=447626

[steve4102]

I did read the manual and I disagree with Western.
Lyman 48th had this to say on page 137:

222 Remington

55 grain JSP
Powder Max Load Velocity Pressure (CUP)
748 24.2 2885 44,200

55 grain #225415 (#2 alloy)
Powder Max Load Velocity Pressure (CUP)
748 25.0 2881 25,000


Might want to turn the page to 138.

55gr #225646 #2

748, 26gr = 3058fps @ 42,700CUP

Seems to me that data you quoted is an anomaly or a Mis-print.

[Bullshop]

My faith is in my experience and ability to read the signs of what is happening with my loads. The manuals are a handy reference to find a safe place to start but beyond that have little to do with what is happening with your or my particular gun.
It really matters not which will produce what pressure as long as you read that pressure and load accordingly.
The point that is being argued is irrelevant.

[Whitespider]

Seems to me that data you quoted is an anomaly or a Mis-print.

Hard to say... but it does make ya' wonder...
I mean, a .222 Remington load at only 25,000 CUP listed as maximum??
It sure does throw up a red flag though... don't it??
*

[RPRNY]

And yet the 55gr 225646 #2 alloy load (page 138) Is is still lower pressure (at 2 grs more powder) than the 55 gr jacketed load.

[jonp]

I may understand if a jkt bullet maker tried this out to subtly push their product but I don't see what Western has to gain from putting out a statement like that. They must have the pressure equipment to test out their powders.

[steve4102]

And yet the 55gr 225646 #2 alloy load (page 138) Is is still lower pressure (at 2 grs more powder) than the 55 gr jacketed load.

Yes it is, now go to page 323 and 324 and look at the 9mm 147gr data.

Titegroup Lead=2.8gr @30,300CUP...Jacketed=3.6gr @31,900CUP

Bullseye Lead=3.5gr @31,600CUP...Jacketed =3.9gr @29,900CUP
...Jacketed used .4gr more powder with Less Pressure.

700X Lead=3.3gr @32,200CUP...Jacketed=3.6gr @30,700CUP
Jacketed used .3gr more powder with less Pressure.

Universal Lead=3.4gr 31,000CUP...Jacketed=3.5gr @29,200CUP
...Jacketed used .1gr more powder with less Pressure

Unique Lead=3.8gr @31,800...Jacketed=4.5gr @29,100CUP
...Jacketed used .7gr more powder with less pressure.

WSF Lead=3.9gr @32,100CUP...Jacketed=4.4gr @30,800CUP
...Jacketed used .5gr More powder with less pressure

HS-6 Lead=5.0gr @31,900...Jacketed=5.8gr @30,500CUP
...Jacketed used .8gr More powder with Less Pressure

AA#7 Lead=7.1gr @29,300CUP...Jacketed=7.2gr @29,000CUP
...Jacketed used .1gr More powder with less Pressure

Blue Dot Lead =5.9gr @31,200...Jacketed=6.6gr @28,600CUP
...Jacketed used .7gr more powder with less pressure.

In all of these examples thye lead bullet used less powder to produce higher pressures than the jacketed bullet.

[303Guy]

I don't understand how say at 40,000 psi one typ can exert more pressure against the barrel wall than the other. Neither can exceed the chamber pressure and once the pressure is sufficient to obturate either type the the outward pressure of the bullet sides to the barrel should be the same.Actually, a softer boolit will exert more sideways pressure on the bore with the same chamber pressure as a jacketed bullet. There's an experiment one can do to demonstrate this. Take a cloth patch and roll it into a ball and push it into the bore, then another and another until they form a plug that cannot be moved. The harder one pushes on them the faster they grip the bore. To remove one needs a thin hooked device to pull the patches out from the other side. The first ball puts some resistance on the second one which expands outward a little which resists the next one even more and so on.

But things are not equal. Just changing the lube will change the friction as will the alloy hardness (ability to resist outward expansion). Then some jacketed bullets will smear in the bore - that's no longer friction but shear strength plus friction. So the bore condition will have an effect. That means the test barrel results may differ from our results.

I don't think any of the manuals are wrong or have typo's - the results were as per their test barrels.

Then we have differences in bullet/boolit shape. A jacketed bullet with its longer ogive has to move further before it seals the bore allowing more gas leakage.

[JonB_in_Glencoe]

If a gun's barrel has a J-word "stuck" midway down it, and then a cast boolit is then shot through the same gun...

WHICH PROJECTILE CAUSES THE MOST PRESSURE ?
:twisted:

[freebullet]

Lol, I bet cast makes higher pressure than titainium bullets too, lol.

Bullet profile, oal, the gun fired from, cases used, primer used, powder used, and other variables affect pressure. I've found book data too hot for my tastes that conflicts with other books. Posting all the charge weights means nothing because it doesn't give the whole picture.

I guess nobody at western has ever pushed a jacketed bullet or cast boolit out of a bore or they wouldn't make a statement like that, otherwise I want some of their alloy.

[Reg]

OK, just to throw a little gas on a open fire, referring to a article from the October 1993 Guns and Ammo by Ross Seyfried. Ultimate Cast Handgun Bullets. Yes this came from a comic book but I think Ross Seyfried has more than proven his ability and no, this isn't EXACTLY what the discussion is but I think there is a shown relationship.
In referring to two identical bullet molds he had cut, 305 gn., 44 caliber, one plain base and one gas checked. Both loaded with 21.9 gn. H-110 and then sent to Hodgdon for pressure and velocity testing.
I quote " The plainbased bullets averaged 5,000 PSI or about 13 percent more pressure than the gas checked ones, while gaining only 37 FPS or 2.6 percent more velocity. At the same time the standard deviation of the plainbased loads was more than double that of the gas checked ones. "
Page 61
There is a graph in the middle of the page showing two different weights of bullets tested both plain base and gas checked showing actual pressure's and velocity's.
The 305 gn. w/gascheck showed 33,000 PSI @ 1,383 FPS
The 305 gn. plainbase showed 38,200 PSI @ 1,346 FPS
This from the Hodgdon lab.

He also goes on to state that in general the gas checked bullet will tend to shoot more accurately but lets not go there !!
Point being in a round about way he backs up the concept guilding metal riding down the bore tends to do it slicker than just plain lead.

[RobS]

Point being in a round about way he backs up the concept guilding metal riding down the bore tends to do it slicker than just plain lead.

and/or more deformation/obturation of the lead boolit without GC at whatever BHN it was. more variables here

[steve4102]

I guess nobody at western has ever pushed a jacketed bullet or cast boolit out of a bore or they wouldn't make a statement like that, otherwise I want some of their alloy.

That statement is idiotic at best.

I guess you have never tested ammunition with expensive Pressure Testing Equipment, otherwise you wouldn't make an idiotic Statement like that.

If You have $$$ Pressure$$$ testing equipment and actual data, I apologize. Please post your Pressure data for all to see.

[JSnover]

Ah, but you are again forgetting, Western Powders has Millions of dollars invested in pressure barrels and pressure testing equipment and thousands of hours and pages of Actual Data.

And Lyman doesn't? What do they have, some bearded mountain hick with a bullet-ridden tree stump? My apologies to bearded mountain hicks. I come from a long line of hicks.
Indeed, their data falls on both sides of the fence. That's why I thought it was somewhat foolish of Western to publish a blanket statement like that when virtually every manual proves them wrong. Like I said, it depends...

[JSnover]

Here is a comment from a Handloader that has a Pressure testing system not just an opinion and a PC.

In every test I run with a pressure gun (piezo sensor), with the same powder load lead bullets gave higher pressures respect to jacketed ones; and with the same pressure, lead bullets gave higher speeds.

Link, Post #8

http://forums.1911forum.com/showthread.php?t=447626

Ok, so there are at least two pressure testing systems operational in North America, three if Lyman owns one. I doubt the author has tested as many loads. His data is accurate and correct, but only as far as it goes. In fact - on that same thread - you had this to say: "This is not necessarily true, in fact in many instances just the opposite is true." So which is it? Are pressures higher with lead or with jacketed? I'll help you out… It depends.
Pressures are generally higher with cast but every time I flip to a different cartridge in my manual I manage to find a case where the opposite is true.

[freebullet]

That statement is idiotic at best.

I guess you have never tested ammunition with expensive Pressure Testing Equipment, otherwise you wouldn't make an idiotic Statement like that.

If You have $$$ Pressure$$$ testing equipment and actual data, I apologize. Please post your Pressure data for all to see.

Guess that's a retard statement at best since you are talking trash and didn't provide any of the data from your super duper scientific testing either. Back under your rock you go.

[Bullshop]

How about jacketed to jacketed. Are pressures higher, lower, or the same with steel jacketed bullets than with guilding metal jacketed bullets?
If the analogy presented for lead/jacketed is true then steel jacket bullets would have to produce lower pressure because they are harder.
Well?

[JSnover]

Might want to turn the page to 138.

55gr #225646 #2

748, 26gr = 3058fps @ 42,700CUP

Seems to me that data you quoted is an anomaly or a Mis-print.

Take the discrepancy up with Lyman, I trust them and their equipment more than your opinion. There's another alleged misprint in the 45-70 section for Ruger #1 and #3 rifles. 53 grains of 322 produces 2,000 cup less under a 405 grain cast boolit. Velocity is almost identical to the 400 grain jacketed bullet.

[steve4102]

And Lyman doesn't? What do they have, some bearded mountain hick with a bullet-ridden tree stump? My apologies to bearded mountain hicks. I come from a long line of hicks.
Indeed, their data falls on both sides of the fence. That's why I thought it was somewhat foolish of Western to publish a blanket statement like that when virtually every manual proves them wrong. Like I said, it depends...


Of course Lyman has Pressure testing equipment, I never said otherwise. In fact if you would read you will find I posted Lyman Pressure tested data for the 9MM in post #85.

In post #85 it shows that the Lead bullet produced higher pressure with less powder.

[steve4102]

Ok, so there are at least two pressure testing systems operational in North America, three if Lyman owns one. I doubt the author has tested as many loads. His data is accurate and correct, but only as far as it goes. In fact - on that same thread - you had this to say: "This is not necessarily true, in fact in many instances just the opposite is true." So which is it? Are pressures higher with lead or with jacketed? I'll help you out… It depends.
Pressures are generally higher with cast but every time I flip to a different cartridge in my manual I manage to find a case where the opposite is true.


Two(2) Pressure testing System in North America? Really??

Nosler has a Pressure lab.

Hornady has a Pressure Lab.

Hodgdon ha a Pressure Lab.

Western Powders has a Pressure Lab.

Barnes has a Pressure Lab.

Alliant/Speer has a Pressure Lab.

ATK has a Pressure Lab or 3.

Lyman has a Pressure Lab.

...and I'm sure I forgot a few.

Yes, I said that and since that post I have been convinced, by those with Pressure Testing Equipment, that with "All things being equal a lead bullet will generate higher pressure than a jacketed bullet".

[Rick Hodges]

[ Yes, I said that and since that post I have been convinced, by those with Pressure Testing Equipment, that with "All things being equal a lead bullet will generate higher pressure than a jacketed bullet".[/QUOTE]

And there lies the rub. All things are NEVER equal.

[62chevy]

How about jacketed to jacketed. Are pressures higher, lower, or the same with steel jacketed bullets than with guilding metal jacketed bullets?
If the analogy presented for lead/jacketed is true then steel jacket bullets would have to produce lower pressure because they are harder.
Well?

Don't forget about copper plated bullets.

[RobS]

Figured the thread could have some more data. I'm not saying one way or the other as it's been tested with labs to show both an increase in pressure/velocities with cast bullets, however not all cast bullets are the same. I know this data is formed with the use of Cast Performance Cast Bullets and their BHN as stated on their site is 18-21 BHN. Other data could have been used with softer bullets, swaged bullets, who knows and there in lies more variables to load data that is published by companies that use pressure testing equipment.


http://i612.photobucket.com/albums/tt206/RobS01/Hodgdon454Casulldata_zps2d517987.jpg (http://s612.photobucket.com/user/RobS01/media/Hodgdon454Casulldata_zps2d517987.jpg.html)

[Bullshop]

What is SFT, and what is CPB ?

[RobS]

What is SFT, and what is CPB ?

SFT = Swift Bullet company jacketed HP and CPB = Cast Performance Bullets a bullet company

found the PDF online finally.........page 17
https://www.hodgdon.com/PDF/Hodgdon%20Basic%20Manual.pdf

https://www.midsouthshooterssupply.com/item.asp?sku=0019245325

[Newtire]

Better check your facts.
Typically the babbitt material covering main and rod bearings contains less than ½% lead (like o.3 or o.4%).
They are a tin based alloy and contain more copper and/or antimony than lead. They work because of a "pressurized" lubricating system that "floats" the crank journals within them. The reason for the "soft(ish)" layered alloys is not for their "slipperiness"... rather so it doesn't destroy the crank when the bearing fails.
I think the engine bearing material is porous so as to hold oil in the pores, otherwise, you would wipe out a crank evertime you started the engine.

[Bullshop]

I wonder why all the listed pressures for the SFT jacketed bullet are all the same at 52,600.
On the first load with the cast boolit on the max load what does the C after the charge weight represent?

[RobS]

C probably stands for compressed load which is interesting as the Cast Performance PB boolit is looking like it takes up more case volume vs the Swift Jacketed bullet since they have the same max charge yet the cast boolit is seated to a longer OAL. I assume the H110/296 load is what they determine as the same since they are only different by lot number (same powder company makes both), the same thing they do with their HP38 and Winchester 231 info. As to why the max charges for the LilGun and 4227 being 52,600..............beats me.

[JonB_in_Glencoe]

Yes, I said that and since that post I have been convinced, by those with Pressure Testing Equipment, that with "All things being equal a lead bullet will generate higher pressure than a jacketed bullet".


Figured the thread could have some more data. I'm not saying one way or the other as it's been tested with labs to show both an increase in pressure/velocities with cast bullets, however not all cast bullets are the same. I know this data is formed with the use of Cast Performance Cast Bullets and their BHN as stated on their site is 18-21 BHN. Other data could have been used with softer bullets, swaged bullets, who knows and there in lies more variables to load data that is published by companies that use pressure testing equipment.
http://i612.photobucket.com/albums/tt206/RobS01/Hodgdon454Casulldata_zps2d517987.jpg (http://s612.photobucket.com/user/RobS01/media/Hodgdon454Casulldata_zps2d517987.jpg.html)

Oh My,
Look at THAT Data. More powder with the CB loads yields similar or higher velocities and less pressure :mrgreen: :mrgreen:
Heck...Hodgdon's pressure meter must be out of calibration :veryconfu

All things can not be equal.

[steve4102]

BULLET WEIGHT
250 GR. LYMAN CAST
Starting Loads Maximum Loads
Manufacturer Powder Bullet Diam.
C.O.L.
Grs.
Vel. (ft/s)
Pressure
Grs.
Vel. (ft/s)
Pressure
Hodgdon H322 .376" 2.500" 24.0 1,534 22,500 CUP 27.0 1,692 27,600 CUP
Hodgdon H4198 .376" 2.500" 18.5 1,408 17,100 CUP 24.0 1,740 26,200 CUP


BULLET WEIGHT
255 GR. BAR JFP
Starting Loads Maximum Loads
Manufacturer Powder Bullet Diam.
C.O.L.
Grs.
Vel. (ft/s)
Pressure
Grs.
Vel. (ft/s)
Pressure
Hodgdon H322 .375" 2.620" 27.0 1,603 25,500 CUP 33.0 1,830 28,200 CUP
Hodgdon H4198 .375" 2.620" 24.0 1,554 21,400 CUP 28.0 1,788 26,700 CUP

This data is from Hodgdon.

Note the Lead bullet used 4gr LESS of H4198 and 6gr LESS 322 to achieve similar pressures.

I would take a screen shot, but I don't know how.

[DrCaveman]

How about this:

What the **** does this whole supposition matter?

You load to book standards, or you generate your own loads based on experience and knowledge of pressure signs. You judge accuracy by where your boolit hits compared to where you aimed, and you judge performance on targets. You then record actual velocities obtained, and if you have the equipment, pressures. Who cares if the pressures are higher or lower if the boolit is performing well?

[Whitespider]

I think the engine bearing material is porous so as to hold oil in the pores, otherwise, you would wipe out a crank evertime you started the engine.

Technically correct... sort'a... "porous" ain't quite the correct terminology.
But that's another discussion...
*

[singleshot]

BULLET WEIGHT
250 GR. LYMAN CAST
Starting Loads Maximum Loads
Manufacturer Powder Bullet Diam.
C.O.L.
Grs.
Vel. (ft/s)
Pressure
Grs.
Vel. (ft/s)
Pressure
Hodgdon H322 .376" 2.500" 24.0 1,534 22,500 CUP 27.0 1,692 27,600 CUP
Hodgdon H4198 .376" 2.500" 18.5 1,408 17,100 CUP 24.0 1,740 26,200 CUP


BULLET WEIGHT
255 GR. BAR JFP
Starting Loads Maximum Loads
Manufacturer Powder Bullet Diam.
C.O.L.
Grs.
Vel. (ft/s)
Pressure
Grs.
Vel. (ft/s)
Pressure
Hodgdon H322 .375" 2.620" 27.0 1,603 25,500 CUP 33.0 1,830 28,200 CUP
Hodgdon H4198 .375" 2.620" 24.0 1,554 21,400 CUP 28.0 1,788 26,700 CUP

This data is from Hodgdon.

Note the Lead bullet used 4gr LESS of H4198 and 6gr LESS 322 to achieve similar pressures.

I would take a screen shot, but I don't know how.

Look again. The longer COL for the jacketed EASILY accounts for the discrepancy.

[singleshot]

Put another way, unless the projectile is seated into the lands, longer COL (cartridge overall length) will result in lower pressure.

[Whitespider]

Do ya' suppose that possibly... maybe... could it be that it ain't as simple as some of y'all wanna' believe it is??
I mean... just throwin' this out... suppose ya' compare a jacketed to a cast and start with low powder charges/pressures. Suppose those low charges ain't enough to obturate the bases of either. Now, as you work up the charge/pressure one base does begin to obturate (who knows which?), and further up the ladder the other does... what do you suppose the pressure comparisons will look like at those different points?? What happens to pressure when acceleration gets to the point where the cast begins to actually slump?? What if it runs short of lube at some point in the barrel?? Does barrel condition (pitting, roughness, etc.) affect the friction coefficient of one more than the other?? Rate of twist?? Free bore and lead angle of the lands??

This discussion has reached the point where no more value can come of it... there's been multiple examples shown where somebody's load date supports one side or the other of it. OK... I get it... or, at least I think I do. Something during testing prompted Western Powders to believe, at least as a general rule, that cast (of like weight) will generate higher pressures at identical powder charges in the barrels they tested (and there's similar statements in the Lyman, and other manuals). But at the same time, every manual I've ever read also states, even warns, there are no hard-fast set rules... every gun is a law unto itself, and variances in reloading technique alone can negate any "general" rule established by anyone (and that includes Lyman, Western, and whoever else).

I know I've seen it go both ways... using typical "observational" evidence as a reloader and amateur (very amateur) ballistition. I don't believe Western stated that as an always, without exception, hard-set fact... heck, even I know better than that...
*

[RobS]

Do ya' suppose that possibly... maybe... could it be that it ain't as simple as some of y'all wanna' believe it is??

I know I've seen it go both ways... using typical "observational" evidence as a reloader and amateur (very amateur) ballistition. I don't believe Western stated that as an always, without exception, hard-set fact... heck, even I know better than that...
*

Exactly and what I mentioned from my beginning post with the variables.....to many examples that support both causes because both exist and labs have proven this as the data is there. People can state whatever they want however fact is there in both directions concerning cast bullet/jacketed bullet load data comparison and there is no absolute and making a statement that is one sided is refuted or supported with lab tested data. It is all there folks.

[Bullshop]

So I have to ask, has any of this changed anyone's mind from what it was regarding this subject before this thread started?
My guess is I think not.

[RobS]

So I have to ask, has any of this changed anyone's mind from what it was regarding this subject before this thread started?
My guess is I think not.

Not mine but then again I seen it from both accounts from the beginning and stand by the fact there is no definable absolute other than proven lab pressure data which of course can be taken into account at each particular lab with such utilized firearm, loaded ammunition and pressure testing equipment.

[BAGTIC]

Compare the Lil Gun loads. It takes 3 grains more powder to achieve essentially the same velocity with the cast aswith the jacketed and it did so with much less pressure.

What we need to see is an identical load with both bullets with the bullets seated to the same depth producing same usable case capacity. There may still be some difference because different ogives will produce differences in bullet travel prior to engaging riflings but that is probably the best that can be done without firing one series from the gun and then modifying its throat for the second series.

[RPRNY]

This has been resolved....several times during this thread. Clearly Western Powders' general statement is incorrect. All other things being equal.... except we have established beyond all reasonable doubt that all other things are never equal.

[Digital Dan]

Y'all lemme know when it's all figured out.

[MtGun44]

And it may be useful to note that those Cast Perf boolits are typically harder than
the hinges of hades, so likely on the high end of boolit pressures.

Bill

[RobS]

And it may be useful to note that those Cast Perf boolits are typically harder than
the hinges of hades, so likely on the high end of boolit pressures.

Bill

Very possibly wrong, they could result in less pressure with higher pressure situations vs a softer boolit.

[Whitespider]

Very possibly wrong, they could result in less pressure...
That's what I've seen, using non-scientific observation as evidence... softer tends to run at higher pressure, and more often higher velocities. I actually ran an unintentional data-collecting comparison of soft vs. hard(er) one time.

When I got my .38-40 Blackhawk I was anxious to shoot it and picked up some Hornady soft-swaged 180 grain SWC's, a week later I bought some hard-cast 180's at a gun show. I'd been shooting the Hornadys with 17.5 grains of Accurate 5744, so I loaded some of the hard-cast with the same charge. I set up my chronogragh using the Hornadys and saw around 1200 fps, primers slightly flattened and zero barrel leading. When I switched to the hard-cast I saw only 1040 FPS, no primer flattening and they leaded the bore... I ended up increasing the hard-cast charge to 19.0 grains, giving me 1150 FPS, slightly flattened primers and barrel leading was near eliminated. Just going on my amateur ballistition observations... the hard-cast required more powder to achieve like pressure, yet still appeared to give lower velocity (shrug).

By-the-way, those hard-cast actually weighed closer to 175 grains (like 177 and the Hornadys a true 180) and measured .4013-.4015 and my Blackhawk barrel slugs .4008, cylinder mouths .4014.
*

[RobS]

Whitespider:

Yeah another part about commercial hard cast that even when sized appropriate there may be leading until pressures increase can often be caused by the crayon lubes used for ease of shipping. A good, quality, soft lube helps negate possible leading due to being of a tougher/harder BHN because if flows more readily from the start of the boolit's journey. Some people have also taken hard cast that come with this crayon lube and have hand dipped with tumble lube to add another layer of lube protection if you will to make up for the less "flow-able" commercial lube.

[RobS]

When I got my .38-40 Blackhawk I was anxious to shoot it and picked up some Hornady soft-swaged 180 grain SWC's, a week later I bought some hard-cast 180's at a gun show. I'd been shooting the Hornadys with 17.5 grains of Accurate 5744, so I loaded some of the hard-cast with the same charge. I set up my chronogragh using the Hornadys and saw around 1200 fps, primers slightly flattened and zero barrel leading. When I switched to the hard-cast I saw only 1040 FPS, no primer flattening and they leaded the bore... I ended up increasing the hard-cast charge to 19.0 grains, giving me 1150 FPS, slightly flattened primers and barrel leading was near eliminated. Just going on my amateur ballistition observations... the hard-cast required more powder to achieve like pressure, yet still appeared to give lower velocity (shrug).
*

This has to do with pressures that are being placed on the cast boolits. As the expanding gasses from the powder being ignited take form there is force or pressure on the base of the boolit and the cylinder throats/forcing cone/bore (in your specific case) then applies force to the front of the boolit. The force on the base of the boolit combined with the force on the nose of the boolit applies pressure on the boolit itself causing it to compress and push outward on the cylinder throat/forcing cone/bore. A softer boolit can be subject or is capable of being compressed to a greater extend vs one that is harder should a powder charge be the same creating more outward pressure exerted to the bearing surfaces of the firearm. Associated then with a softer projectile in your scenario it resulted in a higher chamber pressure which translated to higher velocities as said force compressed the boolit to a point of creating more pressure on the bearing surfaces of your firearm.

[MtGun44]

Hmm. Seems backwards to me. Most boolits are oversized and must be sized down as they enter the
bbl, so harder would take more force to size down.

Bill

[RobS]

Hmm. Seems backwards to me. Most boolits are oversized and must be sized down as they enter the
bbl, so harder would take more force to size down.

Bill

Not necessarily......think about this particular thread in question. Why do labs have data that shows lower pressure rounds such as 45 auto, 38 special etc. that use swaged boolits using powder charges that are equal to jacketed yet the swaged boolit yields more pressure/velocity vs the jacketed. Or some rifle data shooting jacketed with less pressure vs cast boolits with similar weight between the two projectiles and the same powder charges. Then the opposite with the example I pulled from the hodgdon site and posted in this thread.

Considering different hardness levels between cast boolits, the answer lies in what pressures are placed on the cast boolit itself and how hard the boolit is and how much force is placed on the boolit to push it through the throats/forcing cone/bore in revolvers or just the throat/bore in closed chamber systems. It's all relative to each particular situation i.e. load powder charge/primer, boolit (BHN) or bullet (jacketed projectile), firearm in used during testing and the testing equipment...............that is why reload data has both accounts as labs have tested it..........as I said it's all there in each labs data.

[Whitespider]

Seems backwards to me. Most boolits are oversized and must be sized down as they enter the bbl, so harder would take more force to size down.

You're assuming that peak pressure is developed as the boolit enters the rifling and is being "sized" down. Under some certain conditions that may possibly be true... but likely it ain't for the majority. It takes time for powder (modern smokeless powder) to burn and reach peak pressure, usually at some point after the boolit/bullet has entered the barrel. That's the main purpose of different powder burning rates, matching that rate to the variables of projectile weight, construction, friction coefficient, desired velocity, barrel length, expansion ratio of the cartridge and some others more technical and/or obscure.

Remember that we're only talkin' 'bout peak pressure here in this thread...

Look at it this way...
Except for some rather minuscule differences between single and double base powders... 10 grains of Bullseye contains the same amount of energy as 10 grains of IMR7828, the difference is in how fast it releases that energy (and it should be noted that the rate of release may/can/will change from cartridge to cartridge, or even with different boolits/bullets within the same cartridge).
*

[MT Chambers]

Maybe this explains why AA powders never make it on to the store shelf??

[Quiettime]

When I first got a .45 Colt revolver, I did not have any cast bullets in my stock. All I had .45 cal was some FMJ 230 Winchester bullets. I made some loads using data for 255 gr cast (lighter bullet, should be safe right?) using Universal Clays powder. OAL was adjusted by eye, based on the beginning of the ogive placed just ahead of the mouth of the case. Went to the range. Piff piff! Recoil was mild to say the least. You could almost see the bullets going downrange and they were not penetrating a piece of 5/8 plywood from 25 yards.

What is interesting is there was a LOT of unburned powder particles in the gun and left in the cases...

Did the jacketed bullet slow the load down because it is harder to deform?

Did the lighter weight bullet not create enough resistance to raise the pressure enough to burn the powder?

Did the different seating depth not create enough pressure?

Did the different bearing surface have an effect?

I'm with Whitespider, I think there are too many factors involved to definitively say this or that. You can take two molds, one smooth sided and one with a lot of lube grooves both the same weight and have totally different bearing surfaces. Hollow base, bevel base, plain base...Does the chamber have a lot of freebore, a sharp leade angle, compound leade etc etc etc

One thing I learned for sure that day is you cannot substitute lead data for jacketed data or vice versa!

[JonB_in_Glencoe]

Quiettime,
I'm not sure if your questions are rhetorical? or if you are truly looking for an answer?
First, some older 45 colts have larger specs...like .454" you could have some issues with severely undersized bullets and lots of blowby.
Second, light loads of "shotgun" powder in pistols are notoriously dirty, because those powders are designed to burn clean at a certain pressure, anything less you get an incomplete burn.

[Whitespider]

...light loads of "shotgun" powder in pistols are notoriously dirty, because those powders are designed to burn clean at a certain pressure, anything less you get an incomplete burn.

That has problems flying in my world.
Most shot-shell loads run in the 7500 to 10,500 PSI range... even starting loads for the .45 Colt meet that criteria.
The Hodgdon website doesn't list 255 grain cast or 230 grain jacketed... but they do list 250 grain cast and 225 grain jacketed.
Interestingly the Universal Clays starting load for the 225 grain jacketed is .1 less than for the 250 grain cast (6.4 vs. 6.5).
I don't know where Quiettime got his data, or what powder charge he used... but, going on Hodgdon's web data, it should have been close enough for shooting dirt clods.
*

[JonB_in_Glencoe]

That has problems flying in my world.
Most shot-shell loads run in the 7500 to 10,500 PSI range... even starting loads for the .45 Colt meet that criteria.
...snip

A quick look in my Lyman manual had a starting load of Clays for 255gr. cast in 45 colt developing 8700 CUP. Then put a lighter weight undersized J-word in there and maybe the pressure could be less than 5K ? Just a guess.
Quiettime listed no details, so it's hard to guess, I was trying to help him out.
Jon

[singleshot]

The energy of activation and first few ms of burn are critical. A shotgun is designed to have zero blow-by during the critical ignition and initial pressure build phase. In fact, there is virtually none until the gas seal exits the shell. In a 45 LC, if that initial ignition and pressure build is lost (probably due to an oversized chamber in addition to the oversized bore) there simply won't be enough energy of activation to get a decent burn.

And velocity is not about peak pressure, it's about the area under the curve, so to speak.

[303Guy]

You're assuming that peak pressure is developed as the boolit enters the rifling and is being "sized" down. Bingo! And therein lies the answer.

There still remains gas leakage with jacketed's which would surely reduce peak pressure. Someone once embarked a project to turn a 270 Winchester into a magnum and to achieve that end he had his custom barrel cut with extra deep grooves to allow gas leakage. He claimed to achieve higher velocity with heavier charges by doing this, relying on leakage to keep peak pressure within allowable limits. He used more of a slower powder.

[Larry Gibson]

And velocity is not about peak pressure, it's about the area under the curve, so to speak.

That is correct.

If you saw time/pressure curves of low end target/SASS loads you see just how uneven and erratic powders burn, even the fastest of them.

Larry Gibson

[sawzall]

Better check your facts.
Typically the babbitt material covering main and rod bearings contains less than ½% lead (like o.3 or o.4%).
They are a tin based alloy and contain more copper and/or antimony than lead. They work because of a "pressurized" lubricating system that "floats" the crank journals within them. The reason for the "soft(ish)" layered alloys is not for their "slipperiness"... rather so it doesn't destroy the crank when the bearing fails.

The soft coating on bearings is for "embedibility" or the ability to capture small particles and allow them to be driven into the bearing instead of the crankshaft / camshaft.

[303Guy]

The soft coating on bearings is for "embedibility" or the ability to capture small particles and allow them to be driven into the bearing instead of the crankshaft / camshaft.Is that correct? "Embedibility" sounds like small particles will get embedded and abrade the journals. I'd have thought the material used has a high fluid friction so as to trap the oil film and force dynamic lubrication.

[sawzall]

Is that correct? "Embedibility" sounds like small particles will get embedded and abrade the journals. I'd have thought the material used has a high fluid friction so as to trap the oil film and force dynamic lubrication.

If the bearing surface is too hard, the particles will flow between the surfaces and abrade both. The soft layer of "babbit" type material allows the particles to be driven down low enough to be covered by the hydrodynamic wedge of oil that lubricates the bearings and journals. We are talking tiny, almost microscopic particulate matter here though. Bigger pieces will still get embedded into the bearings but will exceed the film thickness of the oil and score the crank or cam journals. Bearings have 3 layers to them. The steel backing, or shell, gives them strength. A layer of a copper alloy gives them "conformability" which allows the bearing to kind of adapt to imperfections in the bearing journal and the final, very thin layer of the babbit (not actually babbit anymore) for the embedability described above. It's a fine line for bearing manufacturers to build bearings that offer good protection and last a reasonable amount of time. And an engine bearing should really never in it's service be run "metal to metal" as stated by another poster in this thread. When they are run dry in such a fashion, catastrophic failure results. They are lubed with assembly lube on initial assembly and then generally prelubed with oil pressure before first start up. Then, when the engine is shut off, a very small amount of oil stays between the surfaces giving initial protection on start up which really is a very light load on the engine. They start pumping oil as soon as the engine begins turning over and build oil pressure. A gauge doesn't always reflect this. It does take a little bit of time for the oil to form the hydrodynamic wedge that actually protects the surfaces when running which is why you should never rev an engine high right as you start it. This is when most normal bearing wear occurs, unless there are other problems with the engine.

[BAGTIC]

Similar to gasoline where low octane gas actually contains more energy than high octane gas. The advantage of high octane is that it can be used at higher compression (pressure) levels before it begins pinging (detonating). Higher pressure levels permit more power to be developed within the same engine displacement (case capacity).

[TXGunNut]

I think the engine bearing material is porous so as to hold oil in the pores, otherwise, you would wipe out a crank evertime you started the engine.

Ummm...No. But let's not get any more off-topic here.

[steve4102]

Sorry to revive this old Thread, but I recently received and Email from Western Powders on this subject. Thought you might be interested in their response.

BTW, the link in the OP (1) is broken. Maybe they removed it due to error?

My Question,

With all things being equal, Case, powder, powder charge, primer, OAL and bullet dimensions,
Which type of bullet generates more pressure/velocity?

Their Answer,

Jacketed bullets will create a higher pressure, because the copper jacket is harder to conform and push down the barrel compared to a lead bullet.

Go Figure?

[Larry Gibson]

Not hard to "figure", it is fact.

Larry Gibson

[W.R.Buchanan]

One thing I have found thruout my life is that a lot of times people think the are saying something that comes out completely differently when written. Our president does this all the time, and it works well for him.

However if this guy actually believes this, then he is obviously mistaken and should be duly chastised.

I have a book on Cartridge Conversions written by a very knowledgeable gun writer. I have found several instances where the information given was totally incorrect. .375 Whelen being the first one I can think of off hand. Only the .375 AI Whelen was correct and not because PO Ackley redesigned it, but simply because he made it the way it was supposed to be in the first place, and then put his name on it.

Turns out the original source for the bogus information was none other than Phil Sharpe. Who obviously thought that all of the Whelen cartridges were simply necked up .30-06 cases. True up to the .35 but the .375 and .400 were both blown out to create more of a shoulder.

Apparently this was not common knowledge back in the day as Whelen specified that his conversions only be done by a select few gunsmiths who obviously knew the secret.

I have found many such instances in this book.

My point about all this is that now this whole book is suspect, and I don't know what is correct and what is not, and have to consult other sources for backup information. I can usually figure out where I need to go but that doesn't mean everybody can.

This is a problem with the internet and one must always be willing to question a source if what they are saying doesn't make sense.

Randy

[dondiego]

Now I am confused!

[curioushooter]

So to revive this thread???

If all the other variables are made to be as equal as possible, lead alloy bullets of usable harnesses will generate lower pressures than will gilding metal jacketed bullet?

It has always seemed likely to me.

But I would be interested in any testing specifically to answer this question.

It seems to me that trying to use published load data is useless. Most published loads for lead bullets are made deliberately low-powered because the assumption (particularly in rifles) is that lead bullets cannot be driven hard anyway. If some reasonable data with pressure info and similarly shaped bullets were available, I suspect it would be found to be cartridge/platform specific.

In my experience the difference is small and can go different ways. I have examples of incidental observations that make me think that perhaps gas checked bullets generate less pressure than plain base, but cannot find a single example of a situation where I think a gilding metal jacketed bullet of same weight was making more less pressure with a given charge.

I have shot hundreds of 357 loads of the Lee 358-158-SWCGC bullet and the Lyman 358429 which when cast out of the same alloy (16:1) will weigh exactly the same (168 grains) after being sized and lubed (Felix's lube) and the Lee has its expensive copper diaper applied.

Shooting the same loads of the the same powders (2400, Win296, and Accurate#9) I consistently get about 25-50 FPS more out of the Lee bullet (when crimped at groove is also seated deeper leaving less powder space). I used to think that it was because of the higher peak pressures due to the deeper seating. But it may have been because the copper diaper reduced frictional coefficients or obturation.

[rking22]

You were right the first time, reducing powder space will increase pressure and therefore velocity. GC or plain base in the revolver will not be enough different to exceed shot to shot variation. Easy test is to shoot the same bullet checked and not. I have the mold ,NOE 2gc 2 pb. But not enough motivation to do the test. Still work full time, maybe after retirement.

[curioushooter]

If you don't check the bullet it weighs about 3 grains less, so that won't work
If you have a mold that throws pb and gc that would work.

[longbow]

I'll toss in my two cents worth here... and that is probably more than it is worth.

In my experience over the years and for cartridges I have reloaded, I have not seen signs of high pressure using "J" bullet load data under cast boolits. My previous understanding and belief is that the easier engraving lead generates less pressure than jacketed bullets, all else being equal.

Fairly recently however there has been discussion that the obturation of lead boolits can result in higher chamber pressures due to increased bore friction than a jacketed bullet with same load data. The first post in this thread comments on the fact that gilding metal has less friction on steel than lead boolits which I highly doubt unless there is no lube on the lead boolit.

I can buy into the obturation causing higher pressures argument to an extent.

However, this is just my opinion based on my experience. Surely there have been pressure tests done to compare? Why should we be operating on opinion here when all a guy has to do is pressure test a few rounds loaded identically with equal weight boolits both jacketed and cast?

I am thinking that Larry may have already done this. If so do you have results you can share with us Larry? And if not are you willing to do some testing of cast versus jacketed... and maybe plain base cast, gas checked cast and jacketed to determine comparative pressures with all else equal?

I make this valid I suspect we'd have to look at hand gun cartridges, large bore rifle cartridges like .45-70 where cast boolits are commonly loaded to max. jacketed pressures/load data and probably smaller bore higher pressure cartridges like .30-06 loaded to max. normal cast velocities or downloaded jacketed velocities if cast can't be loaded to equal jacketed velocities.

So maybe a little more complicated than just loading and pressure testing a few rounds but not a lot. Would 10 of each give us enough info? Should be indicative of trends anyway.

If limited to one cartridge I'd go with .45-70 loaded mild to wild with cast PB and jacketed.

If we are going to run a pool on highest pressure my money is on jacketed bullets!

Like I said, just my opinion and 2 cents worth.

Longbow

[45-70 Chevroner]

I wish I could put this at the beginning of the thread. "Why do jacketed bullets wear out barrels faster than cast boolits, actually I'm not sure you can wear out a barrel with cast boolits"

[Larry Gibson]

"Easy test is to shoot the same bullet checked and not. I have the mold ,NOE 2gc 2 pb. But not enough motivation to do the test"

I recently ran just such a test with the NOE 30 XCB bullet checked and unchecked bullets from the same GC & PB mould. The results were posted.

"I make this valid I suspect we'd have to look at hand gun cartridges, large bore rifle cartridges like .45-70 where cast boolits are commonly loaded to max. jacketed pressures/load data and probably smaller bore higher pressure cartridges like .30-06 loaded to max. normal cast velocities or downloaded jacketed velocities if cast can't be loaded to equal jacketed velocities."

I can run this test easily enough. I have on hand;

For 32 H&R: 313631 105 GC and 100 gr half jacketed Speers.

For 357; 158 Desperado cast and 158 Speer JSP

For 44 Magnum; 429360/242 gr, Laser Cast 240 SWC and 240 gr XTPs.

For 45 Colt; 250 gr cast and 250 gr XTPs

For 30-30; RCBS 30-150-FN or 311466 and Win or Speer 150 JFPs

for 45-70; 457124 and Speer 400 JSPs

Name your poison........

[Texas by God]

Anyone who has ever stuck a jacketed bullet in a barrel knows the answer to this[emoji41]

Sent from my SAMSUNG-SM-G930A using Tapatalk

[unique]

Well I have not read thru all 8 pages so maybe this was already raised...anyway my experience is that cast lead bullets tend to give higher pressures in 357 magnum which I contribute to the fact that cast tend to obturate and seal the bore better than copper jacketed which also tend to be a little undersized in the 357. Loading data from various databooks typically back up this view.

If the cast and copper jacket bullet seal the bore equally well then the copper jacket would certainly have the higher pressure. I am just not convinced that a copper bullet will seal as well, atleast in the 357 mag.

Bottom line is when speaking of ballistics the details & specifics really do matter.

[JSnover]

I wish I could put this at the beginning of the thread. "Why do jacketed bullets wear out barrels faster than cast boolits, actually I'm not sure you can wear out a barrel with cast boolits"

I'm not sure if copper has ever "worn out" a barrel by itself. I believe people tend to load them hotter, thereby wearing/burning the throat prematurely.

[GregLaROCHE]

So what about PCed boolits?

[Bass Ackward]

Ha, HA!, ha ha. Boy have I missed these discussions. On the other hand, I haven't cause nothin is ever solved. Gotta watch them "absolutes". I always said, "no rules". I was wrong. Their is one, "start low & work up." Found in every reloading manual, from every company, since the beginning. Just because of discussions like this one.

[BNE]

I wish we had more of these discussions. While I agree they don’t always lead to concrete rules, they do teach us how to think and how to approach problems / questions we face when reloading. And how to call BS when ignorant people make stupid claims.

I have and continue to learn a lot from this sight. That’s why I keep coming back.

[JonB_in_Glencoe]

Sorry to revive this old Thread, but I recently received and Email from Western Powders on this subject. Thought you might be interested in their response.

BTW, the link in the OP (1) is broken. Maybe they removed it due to error?

My Question,

With all things being equal, Case, powder, powder charge, primer, OAL and bullet dimensions,
Which type of bullet generates more pressure/velocity?

Their Answer,

Jacketed bullets will create a higher pressure, because the copper jacket is harder to conform and push down the barrel compared to a lead bullet.

Go Figure?





If only Western Powders would have added the following to the end of Their Answer.

,Until it isn't.



:p:p:p

[GhostHawk]

Bingo! Copper bites, Lead slides.

Ask any flint knapper why he has copper tools, boppers, pressure flakers, etc. Because it bites, grips the stone.

[longbow]

While it may be true there are no absolutes and if Larry tests two or three different cartridges, will that provide definitive answers for all cartridges? Likely not but I think we'd learn something here and if a handgun cartridge say .44 mag. or .357 mag (tested in rifle barrel?), straight wall rifle cartridge like .45-70 and a bottleneck rifle cartridge like .308 or .30-06 were used we'd have the straight walled handgun cartridge data for a popular caliber, info on a rifle caliber that commonly sees equivalent load data for jacketed and cast boolits and info for a high pressure bottleneck cartridge. Larry mentions .30-30 which runs at somewhat lower pressure than .30-06 or .308 but should still be representative and again is a popular cartridge.

To try to test for all conditions and from small bore to big bore would be a daunting task so a few representative cartridges to test would make sense... to me anyway.

Kinda seems like Larry gets asked these questions a lot and it is very generous of him to offer to do some testing as it all takes time, effort and money to do. If there is a cast boolit caliber I can help with I am quite willing to cast and send boolits to Larry for testing if he wants. Moulds I have that might be suitable for this test: Lyman 31141 170 gr. FP GC, Mihec 434640 PB with HP pins for .44 mag (270 gr. solid), Mihec H&G #503 (.434") PB HP 258 gr. solid. I also have the NOE 316299 GC clone for my .303's but that is a bit of an oddball size (I'd like to see it tested in .303 beside jacketed bullets but...).

I think it would be an interesting test and well worthwhile.

Longbow

[swheeler]

Ha, HA!, ha ha. Boy have I missed these discussions. On the other hand, I haven't cause nothin is ever solved. Gotta watch them "absolutes". I always said, "no rules". I was wrong. Their is one, "start low & work up." Found in every reloading manual, from every company, since the beginning. Just because of discussions like this one.

John-John-John there you go trying to use good sense.

[Larry Gibson]

longbow

"Larry mentions .30-30 which runs at somewhat lower pressure than .30-06 or .308 but should still be representative and again is a popular cartridge."

I mentioned the 30-30 because a cast 170 gr bullet can be shot over the max load for 170 gr jacketed bullet w/o other variables entering in. Doing so in a .308W or 30-06 can raise those other variables.

Sorry, but I got a little lost since I read "start low & work up." ...... trying to figure out how THAT is relevant to the question of this thread; "All things being equal do lead bullets generate more pressure than jacketed bullets?" that the OP asked in his original post.........




.....

[6.5 CM]

On the 375 Whelen observation. Anyone who owns WILDCAT CARTRIDGES can read Mike Petrov's whole chapter on the 400 Whelen and how WITH THE CORRECT G&H/WHELEN chamber there is never a headspace problem.

Larry, thanks for your thread on Berdan conversions AND of course you are correct, there is no way an equivilant cast load has more pressure than jacketed. Next we'll read that a Model A has a higher compression engine than a 427 Ford side oiler !

Tom McHale sez: "Even among bullets with the same overall weight, performance can vary widely, often as a result of friction as a bullet travels down the bore. As a simple example, it’s easier to push a soft lead bullet down the barrel than a hard copper jacketed one." Easier to push means less pressure. Try slugging a bore with a jacketed bullet !

[Peregrine]

I can run this test easily enough. I have on hand;

...


Name your poison........


Is no one else going to take you up on this???

As much as I'm sure most of us here have internalized the idea that a cast boolit will produce less pressure than a j-word of the same weight all less held equal, we can hardly turn up the chance to get some number to get an idea of the magnitudes of the difference!


Test the 30-30 and the .44, and at two charge levels for each; one nice and mild and one on the spicy side.

Having comparative pressure data for both a pistol and a rifle cartridge at both the lower/higher end would substantially elevate the quality of this discussion and make for a great reference to point people towards in the future.

So how about it? Don't make me beg Larry. :p

[Gohon]

Might surprise some of you that in 1988 while doing a write up about his beloved 357 magnum, Skeeter Skelton stated, with all things being equal, that a plain base bullet would would create more pressure than a gas checked bullet. He went on to say that a soft cast bullet would also create more pressure than a hard cast bullet. Food for thought...

[6.5 CM]

Did Skeeter have pressure transducer data to prove that or was he reading tea leaves ?

[Larry Gibson]

We've already determined by actual testing and measuring the pressure that PB vs GC'd bullets really doesn't make any difference pressure wise. As to "a soft cast bullet would also create more pressure than a hard cast bullet" we may just have to test that one also. I really hate to do that to Skeeter as I've always enjoyed his writings and musings but a lot of the old time writers did state what they thought was or would happen w/o any real testing. They also promulgated each others myths, old wife's tales and tea leaf readings. The writers these days along with many on forums still do the same. Given the ready availability of chronographs and even pressure testing equipment we'd expect a more serious approach to fact finding on those old promulgated myths.........

Peregrine

No need to beg, I'll begin loading some tests for the 30-30 and 44 magnum. Might do the 45-70 also.

[longbow]

Larry:

Nothing wrong with .30-30 and I understand your logic. Same logic I had for the .45-70. I mention .308 or .30-06 as they are common and will produce pressures well above "normal" cast boolit pressures for "extreme" cast boolit pressure/velocity. I am thinking alloy hardness will play into this some too. If the alloy is really hard it will not obturate much if any and that would be one of the issues in bore friction with cast boolits. A soft(ish) alloy or higher pressure takes care of that.

And I suppose a qualifier here. When I mention .45-70 I am thinking high end loads of at least Marlin 1895 level with PB boolits compared to jacketed. I used to run my 1895 and Siamese Mauser right to the top end of their respective load range with PB boolits so they were seeing high enough pressure to obturate ACWW. You have already commented on alloy hardness so I'm guessing that is covered.

This should be interesting regardless of outcome as we should have some definitive knowledge when you are done. And thanks for taking this on.

Longbow

[Larry Gibson]

The lead alloy has more "friction".......that is one of the "myths".

Our lubed cast bullets ride the bore on a coat of lube regardless that the alloyed bullet has a much lesser friction coefficient. If we recover such fired alloy bullets that went into the barrel .001+ over groove diameter we find they are .002 - .005"+ under groove diameter after exiting. They do not "seal" the bore with bullet alloy on barrel steel contact. Ergo there is really no obturation but actually swaging down of the cast bullet instead.

Jacketed bullets do not "ride" on a layer of lube and there is bullet jacket to barrel steel contact. Along with the fact that the jacketed bullet is much harder than a cast bullet and requires greater pressure for the rifling to engrave the jacket, for the bullet to swage down if over groove diameter and the jacketed bullet has a greater friction coefficient and is in contact with the barrel steel.......that is why the pressure is higher with a jacketed bullets using a given load all other things being equal.

[swheeler]

I found this on 45 ACP, same weight bullet with cast v jacketed......https://wwpowder.com/244-2/232973

[swheeler]

You will notice that both are loaded to same OAL, max charge for 230 FMJ 5.6grs and 19.7k psi, 230 Lead RN max charge 4.9 grs and 20.1k psi. Wow .7 grs more powder is a LOT in the 45 ACP case. The lead bullet is .452 dia and the jacketed std .451, makes you think about "blanket" statements doesn't it.

[Winger Ed.]

Like so much I do, its not very Scientific, but a simple test should answer the question:
Load a normal, safe, and sane load with a jacketed bullet, the same charge and similar/same weight of a cast one.
After firing them, look at the primer. My guess is the cast load will show less 'flattening' from pressure.

[Larry Gibson]

You will notice that both are loaded to same OAL, max charge for 230 FMJ 5.6grs and 19.7k psi, 230 Lead RN max charge 4.9 grs and 20.1k psi. Wow .7 grs more powder is a LOT in the 45 ACP case. The lead bullet is .452 dia and the jacketed std .451, makes you think about "blanket" statements doesn't it.

Yes the OAL is the same but the information there does not show the seating depth of either. The data does not identify the 230 gr LRN bullet either. Thus we do not know if the seating depth is the same. We do know for a fact (yes this is a "blanket statement") that seating depth affects pressure. Ergo, from that data we do not know, as stated in the OPs question if "All things being equal" applies.

I will test with all bullets seated to the same depth because that affects the pressure and will adhere to "all things being equal"....... the cartridge OAL does not.

[swheeler]

Just pointing out a tid bit, read post #14. Winger Ed you are correct that "reading primers" is not very scientific.

[M-Tecs]

Bullets of the same weight and material with different bearing lengths produce different pressures. The more bullet contact the more friction.

[Loudenboomer]

We've considered our boolits are riding on a film of lube. It would be interesting to note the pressure differences between a squeaky clean barrel and a properly fouled barrel on both cast and jacketed.

[Larry Gibson]

We've considered our boolits are riding on a film of lube. It would be interesting to note the pressure differences between a squeaky clean barrel and a properly fouled barrel on both cast and jacketed.

In the last 10+ year since I've been using the Oehler M43 PBL to measure pressures among other measurements I've conducted 2,541 tests most of which were 10 shot tests. Those were tests were done with 28 different cartridges in 23 different test firearms. That amounts to 22,500 +/- rounds tested.

I always clean the barrels after each test session so they are "squeaky clean" so to speak. While I usually fire at least 2 "foulers" prior to testing a clean barrel my observation is most often the velocity and pressure measurements of the 2 foulers out of the clean barrel fall within the ES of the 10 shot test of velocity and pressure. Also I have conducted 20+ ten shot tests over the last 10 years with a single lot of M118SB in one .308W test rifle w/o shooting any foulers out of the clean barrel. Again, the measured velocity and psi have fallen within the ES for both.

However, while the velocity and pressure measurements fall with in the test ES for both many times the 1st two shots out of the clean barrel were not within the group but sometimes they were.

[Loudenboomer]

Interesting. Thanks Larry.

[JonB_in_Glencoe]

What if this is a paradox ???

> We know that as the pressure increases in a ladder test of castboolit loads, the amount of obturation to the castboolit increases.
> As that obturation increases, I suspect that friction increases.

What if that obturated lubed cast boolit friction surpasses the friction of a unlubed J-word?

My theory on a pressure test comparison of castboolits and j-words:
Light loads will yield results showing J-words creating higher pressures.
Increase the loads to the point that obturation is creating enough friction to surpass that of J-words, then results will start showing castboolits are creating higher pressures.

One great problem of this pressure test, centers on what I have previously stated in this thread [years ago], All things can not be equal, OR BETTER PUT, all "other" things can not be equal.

[JonB_in_Glencoe]

I'd like to add:
One huge issue of "all other things not being equal" is having two projectiles that have the same shape[nose ojive] and same volume and same weight...So when they are seated in the case the same, there will be the same jump to lands (or lack of jump), and same case capacity, so there is a same burn pressure rise. Also the projectiles should be the same diameter, so the case tension is the same.

[sharps4590]

The Lyman Cast Bullet Handbook lists the pressure of some cartridges and loads.

[Larry Gibson]

JonB_in_Glencoe

> We know that as the pressure increases in a ladder test of castboolit loads, the amount of obturation to the castboolit increases.
> As that obturation increases, I suspect that friction increases.

Yes, that is what we've always been told and we've heard it so often it's become "what we thought". But do we really "know" that? Or are we just repeating and believing someone else's assumption? Obturation is defined as swelling to close or obstruct. If our cast bullets are .001 - .003 over groove diameter are they swelling to close? No they aren't. The cast bullets we shoot almost always are over groove diameter. Truth is they are swaged down to go through the barrel. Additionally with lubed bullets they are swaged down to ride on a layer of lube. Thus there is no frictional contact between the alloy and steel. Also the lubed cast bullet is swaged down within one length of bearing surface and begins riding the lube within that one bearing surface of travel. There is no "friction" between alloy and barrel after that. Yes, old BP bullets were dependent on swelling to close and were supposed to obturate as those bullets were smaller in diameter than groove diameter. The over groove diameter bullets we use today do not "swell to close".

Conversely. the jacketed bullet also can be swaged down or even truly obturated if undersize and remains in contact with the steel throughout its travel in the barrel.

Over 12 years ago after I began broaching the subject of the adverse affect RPM had on cast bullets or even jacketed bullets I began serious testing to find out. I received a lot of criticism with "bbbbwwwwaaaahahahaha you changed what you said....." commets from numerous knowledgeable people here. Yes I did change many of my "beliefs" that were based on all the "expert" opinions I'd read for years in books and magazines by well known and respected writers. I, like all of us, accepted them as "fact". As I actually tested what occurs to cast bullets I found many of those assumptions and theories were only based on opinions and guesses at what was happening and were repeated so often by other "experts" and all of us that they became myths and old wife's tales. Frankly I made quite a few enemies on this forum because many self styled experts did not like the truth getting in the way of their own beliefs. I seek the truth and if it proves I am wrong then so be it.

Now to the point here; Do I actually know the answer to the OP's question? No I don't. My own supposition is based on results from other testing that have this far led me to make those suppositions as stated in this thread. Recently I would have said that a GC'd bullet would give more pressure with a given load (all other things being equal) than an identical PB cast bullet. I ran a test on that very question and found there is basically no difference in pressure between the two bullets with the same load. I was wrong and am man enough to admit it and learn. Guess I could have run off to another forum but I've not. So it is with this proposed test. I think I know the answer based on other test results but I have not specifically tested for an answer to the OP's question. If my suppositions are proven incorrect and wrong I will learn from the results and not take any of it as a personal affront.

What if that obturated lubed cast boolit friction surpasses the friction of a unlubed J-word?

My theory on a pressure test comparison of castboolits and j-words:
Light loads will yield results showing J-words creating higher pressures.
Increase the loads to the point that obturation is creating enough friction to surpass that of J-words, then results will start showing castboolits are creating higher pressures.

At what pressure do you think this might occur? In the 44 magnum for a "heavy load" if I load both the 240 gr 44 XTP over the max listed load of 21 gr 2400 and the 429360 (242 gr fully dressed) over the same is that enough pressure? For a lower load I intend on loading both over 8.5 gr Unique. I'm not sure I really want to exceed a published max load for the XTP bullet(?) attempting to find a "point that obturation is creating enough friction to surpass that of J-words" if necessary, do you?

In the 30-30 I was intending on testing a 170 or 150 gr jacketed bullet over a max listed load (probably with H4895) against the same load with a 170 gr 311041 or 150 gr 30-150-FN.

In the 45-70 I was going to use a max load with 400 gr Speer bullets and 400 gr 457483 cast bullet over a max listed TD level load with 4759, a max lever action load with 3031 and a max Ruger #1 level load with RL7.

Any other suggestions?

One great problem of this pressure test, centers on what I have previously stated in this thread [years ago], All things can not be equal, OR BETTER PUT, all "other" things can not be equal.......... One huge issue of "all other things not being equal" is having two projectiles that have the same shape[nose ojive] and same volume and same weight...So when they are seated in the case the same, there will be the same jump to lands (or lack of jump), and same case capacity, so there is a same burn pressure rise. Also the projectiles should be the same diameter, so the case tension is the same.

Those "variables" can easily be adjusted for. Let me say this based on my past experience from other testing indicates unless there is a long free bore to the throat a difference of a few thousandths in bullet jump makes little to no difference in measured psi. What does make a difference in smaller capacity cases is a difference in seating depth (not to be confused with the cartridge OAL). Variations in seating depth in smaller capacity cases (mostly handgun cases) can indeed have a measurable effect on pressure.

My plan in the 44 magnum is to seat both bullets to the same seating depth which will still allow proper crimping. In the rifle cases the bullets will be seated to the crimp groove and properly crimped.

The 44 magnum will be tested in a Contender pistol barrel, the 30-30 in a Contender Carbine barrel and the 45-70 in my Siamese Mauser bolt action rifle.

[Larry Gibson]

BTW; I can push 60,000+ psi in the Siamese Mauser.

[6.5 CM]

Squeeze em' down and they go faster ? That was the theory with the 8x60 Mauser that used .323 Js in .318 bores.

[curioushooter]

I contend that it may be application specific.

I have long used jacketed bullet data to develop cast bullets loads and never really gave it a second thought until I had some pressure signs appear in a 357 mag revolver with under starting loads in 2400 (old data in the Lee Manual). The load manuals are all over with 357 because some go by the mid-90s 35,000 PSI recommendation and others use older hotter max limitation, and some folks (LYMAN) are still working with copper crushers!

In handguns I've loaded cast in 10mm, 44 Mag, 7.62x25, and 32-20 (HIGH PSI Contender loads) and have observed that jacketed seem to make max out with lower charges.

[JonB_in_Glencoe]

Larry,
Thanks for the detailed response. If you do some testing as you have mentioned, I will surely give you whatever support I can when you post about it here.

As to my theory, I have no idea when the friction threshold will be crossed. I do suspect it will happen below Max load data if a soft enough alloy is used.

Lastly, while I hear your words, I just can't picture how the variables can be adjusted for enough, to make all other things the same.

[longbow]

On this line of increased bore friction and obturation...

A few years ago I was doing some informal and not terribly scientific penetration testing for different designs and weights of .44 boolits in my 1894 Marlin. Alloy was basically unknown range scrap which was not quite as hard (subjectively) as COWW. All boolits were cast from this alloy then loaded up.

I started with fairly light boolits and worked up to 300 gr.

During this test I was recovering boolits from end grain fir. This was simply a crude comparison of different designs at max. loads to see what I got. I was surprised to recover a Lyman 429421 that had collapsed in the lube groove almost totally. That is an obvious demonstration that the lead is (or at least can be) yielding under the stress of firing. The 429421 casts undersize for my typical fat bored Marlin (SAAMI spec of 0.431") so could obturate that 0.002" from as cast at 0.429" to groove diameter of 0.431" (measured as best I can to actual of 0.4315") but as Larry says then where does the lead have to go? it is contained by the barrel so if stressed to yield it can only get shorter where it is not supported and that is at the lube groove.

This was a published load but right at max. listing for a jacketed bullet. I got no leading and no sign of pressure... that I saw anyway. So, I have to assume that the boolit did in fact ride on a film of lube since there was no leading and the alloy was too soft for the chamber pressure since there was no sticky brass or flattened primer. That load exceeded that alloys yield strength but there couldn't have been any significant increase in pressure due to bore friction from obturation or I would have had sticky brass, flattened primers or a blow up.

Part of my crude test was to determine if a 300 gr. boolit has more penetration than lighter boolits at higher velocity. Basic question was at what point is case capacity reduced to the point of diminishing returns by boolit weight. My answer is not up to 300 gr. boolits! I didn't go heavier.

I think Larry has definite opinions on what the results of this new test will be and so do I but as Larry says, until the test is done we are basing our opinions on what we think, not what we know or have proved. Doesn't matter which side of the fence you are on, it is just opinion until tested.

I'm looking forward to the results whatever they are as we will all learn something. If I am wrong then I will be corrected and will remember the lesson.

Longbow

[GARD72977]

I have seen some really high pressure from 38spl +p factory loads that seemed to be caused by excessive crimp. I have no idea what the charge would have done with jacketed. The point being you can get high pressure with lead

[swheeler]

I'd like to add:
One huge issue of "all other things not being equal" is having two projectiles that have the same shape[nose ojive] and same volume and same weight...So when they are seated in the case the same, there will be the same jump to lands (or lack of jump), and same case capacity, so there is a same burn pressure rise. Also the projectiles should be the same diameter, so the case tension is the same.

Yes that would make it tough to make "all things being equal" impossible actually I believe. If you take a lead bullet and a jacketed bullet of the same profile and weight the lead bullet will be shorter in length, you may use the same seating depth but jump to lands will be different. Bearing lengths will have to be identical or the test is just more "who shot Tony". If you have two RN bullets for loading the 45 auto, one cast and one jacketed(remember the cast bullet will just about surely be shorter)loaded to the same OAL the jacket bullet will likely be the one with the deepest seating depth because it is longer, that should raise pressure.

[Shiloh]

They used lead and tin based metals called babbitt for pour in place bearings.
For resistance to galling.

Shiloh

[Larry Gibson]

And the list of "alibi's" is growing..........

The problem is "all things" are not equal in what the OP asked. The question was what is the pressure if we substitute a cast bullet of equal weight for a jacketed bullet and "all other things" are equal in the load. The key part was "of equal weight". In a 44 magnum revolver, for instance, I dare say very few here recommend shooting a cast bullet at groove diameter which is usually .429. Nor do hardly any here recommend shooting a .308 sized bullet in .30 caliber rifles. The usual recommendation is to shoot .001 - .003 over groove diameter or to size to the throat diameter. The 44 magnums are most always crimped so a crimp will be used in the crimp groove/canalure. I'll not crimp either the 30-30 as most 30 cal reloads are not crimped. Haven't made up my mind on the 45-70.

Thus I am going to test the bullets the way we use them as I suspect that is what the OP means. As the seating depth in the 44 magnum can be a factor I will endeavor to make that variable as close to the same as I can. I will also test them seated to just the crimp groove irrespective of seating depth. Because it's the way most of us load them the .44 cast bullets will be sized .430, the .30 cals at .311 and the 45-70s at .459.

I think the test loads should reflect the way we actually would load both bullets, not adjust everything for every little nuance we can think of.

I will make "all other things" in the load and in the loading of as equal as we do when loading.

[tazman]

I agree with Larry. We can't exactly match a lead boolit and a jacketed bullet. It is most appropriate if we test things as we normally load them.
That is why I use mixed brass when working up most handgun loads. That is how I use them, so that is how I test them. I undoubtedly get more variation that way, but I also know what I'm working with.

[JBinMN]

I agree as well about the testing as "we would load them". To me, it is the performance as the rounds are loaded & fired in "real life" as they normally would be, rather than a comparison with everything being exactly the same for each one. Since we all are most likely to load them and shoot them that way, than try to match "exactly" in what would not be a "real life" experience or situation.


Looking forward to seeing the test results & Thanks to Mr. Gibson for his efforts.

[longbow]

If we want to get into minutia Larry will never complete the test and we will not get answers. Let's be realistic here. "All else being equal" has limits. Larry has pointed out that for cast boolits most do not size to nominal groove diameter, we cast larger, then size but still at least 0.001" larger than groove. Since that is what most people do that is what should be tested... in my opinion anyway.

Bearing length is likely to be different as well. Do we really care? I don't.

Are factory made jacketed bullets "exactly" the same? No, there are tolerances on all manufactured items. From a given manufacturer they should be very close in diameter (within 10th's of a thou) and profile but are Hornady .30 cal. 170 gr. FP bullets exactly the same as Speer .30 cal. 170 gr. FP bullets? I'd suspect very close in diameter but profile/bearing length, not so much. Let's keep in mind that "close" is a relative term. In guns a 0.001" or 0.002" change in bullet or bore is a large change.

I think Larry started out saying that he'd use equal weight bullets of similar shape and equal seating depth for cast and jacketed bullets so in same brass with same powder charge and same primer we get our comparison results between pressures for cast and jacketed bullets. I think that is the right approach.

Since Larry is doing the test and he has the equipment and experience (certainly more than me) I am content to let him do what he thinks best then learn from the results.

Longbow

[unique]

Let's take my example which is a 357Mag revolver. Peak pressure occurs within the first 1/2" of bullet movement which means before the bullet even enters the bore. My cast lead 160gr are sized .3575 and require a push to clear the cylinder. The speer jacketed 158gr I have measure .3565 and basically are a slightly loose fit but just hang up in cylinder. This is real world, typical for most 357 revolvers, so not hypothetical at all.

When I load the jacketed up with 10.5 gr Bluedot (this is non-canister Bluedot and runs a little hot), the primers are normal flat. When I load the cast lead up with the same load and seating depth, the primers are cratered and show evidence of flowing back thru the firing pin hole. Yes you can read primers visually and learn something about pressure especially when comparing one to another.

Basically, my point is, or maybe better stated, my opinion is, there are few if any hard & fast rules when it comes to ballistics and I do not believe for a moment that someone can run a few tests on a few different calibers and then produce a ballistic axiom.

[JonB_in_Glencoe]

And the list of "alibi's" is growing..........
Alibi's ? ...not me ...not one alibi.
In this case, I just believe All things can't be the same, and have stated so...I stated so 4+ years ago.

When you do your testing and wish to post about it here, I will surely give you whatever support I can.

Thus I am going to test the bullets the way we use them as I suspect that is what the OP means.
I think this is a great plan, and probably the only way a realistic comparison can be done. I hope I can learn something from your results.

[Conditor22]

I am watching with interest.

[303Guy]

Cast boolit riveting could cause undue pressures. Been there, done that. The riveting was into the area in front of the case mouth. It could have been caused by a too soft boolit but I cannot rule out a higher powder charge although that seemed unlikely. I cannot say whether the riveting caused the higher pressure or whether higher pressure caused the riveting.

In the case of 357 magnum revolvers exhibiting higher pressure with cast with higher end loads, I wonder whether it could be due to bump up in or before the forcing cone.

I have recovered boolits that were paper patched that show obturation in front of the patch on the ogive. In this case the patched boolit was being swaged down by the bore, displacing alloy forward while under acceleration forces.

[Larry Gibson]

I have the test rounds loaded. They are in;

357 magnum
44 Magnum
30-30
308W
45-70

There are 280 test rounds loaded in 28 tests. There are 14 loads with jacketed bullets and 14 identical loads with cast bullets. A couple of the cast bullets used weigh a few grains more than the jacketed counterpart but they are all close. A complete description of each load will be in the test result report. I will probably start a new thread with that test result.

That will take 8 - 10 hours of testing given; set up, shooting, target changing, entering data in the computer, barrel cleaning, the usual range interruptions, changing firearms, etc.. I am not sure I will get it all done in one test session. If not then each test of a given load with both jacketed and cast will be conducted back to back to keep the conditions as close to the same as that is the comparison we are looking at; the pressure difference between the same load with jacketed and cast bullets of equal weight.

Next I'll enter all the load data into the Oehler M43's program test format in the laptop (part of the system) I use at the range. I am watching the weather forecasts for a good day and potentially a good day following. I'll report back with the results when the test is complete.

[JBinMN]

Thanks for your update! Looking forward to what results you find!

[OS OK]

I have the test rounds loaded. They are in;

357 magnum
44 Magnum
30-30
308W
45-70

There are 280 test rounds loaded in 28 tests. There are 14 loads with jacketed bullets and 14 identical loads with cast bullets. A couple of the cast bullets used weigh a few grains more than the jacketed counterpart but they are all close. A complete description of each load will be in the test result report. I will probably start a new thread with that test result.

That will take 8 - 10 hours of testing given; set up, shooting, target changing, entering data in the computer, barrel cleaning, the usual range interruptions, changing firearms, etc.. I am not sure I will get it all done in one test session. If not then each test of a given load with both jacketed and cast will be conducted back to back to keep the conditions as close to the same as that is the comparison we are looking at; the pressure difference between the same load with jacketed and cast bullets of equal weight.

Next I'll enter all the load data into the Oehler M43's program test format in the laptop (part of the system) I use at the range. I am watching the weather forecasts for a good day and potentially a good day following. I'll report back with the results when the test is complete.

That's awful nice of you...wish I lived in the area to come over and be your range monkey and help any way I can.

[Peregrine]

Thanks for the update Larry, that greatly exceeds my expectations for testing and i'm pretty excited to see your results. I hope you get good data, good luck!

[longbow]

I'll second what OS OK said... I'd be happy to help out too but the commute is a killer! There is a selfish side to that thought too ~ your bad weather is better than our good weather, currently anyway. It is -2° C outside and raining so the roads are iced up and slick! I would definitely rather be running around on a gun range in Arizona than driving to work in this! Then blowing snow off the driveway for the second time today!

In any case, thanks for doing this and I look forward to your results.

Longbow

[DGV]

Has anyone had the misfortune of a stuck jacketed bullet in a barrel? How about a stuck Lead alloy bullet? Which was easier to move?

[fredj338]

In my experience all else being equal a cast lubricated boolit will give lower velocity of in the neighborhood of 150 fps depending on the type of load and cartridge.
Since I can not accurately measure pressure but can accurately measure velocity I use velocity as an indicator of pressure.
In my own observations lower velocity reads as lower pressure.
Another point I would like to make is this if a jacketed bullet has less friction resistance in its passage through a barrel why then do we not use jacketed bullets to slug our barrels?
I have NEVER had a lead bullet give less vel than jacketed of the same weight, any caliber, with identical powder charges & near identical OAL. Lead bullets always have produced higher vel. If there is less friction, less pressure, less vel, Unless you add more powder to drive the bullet faster. You see this in data for moly coated jacketed, I see no reason to think it is diff with lead.
The slugging thing, not friction but malleability. A lead bullet will more easily be deformed as it is pounded down a barrel. Why they call for nearly dead soft lead & not one of lino.
I would love to see pressure testing done but what is really needed would be dear identical bullets in lead & jacketed for the best comparison. I do know that when I substitute a solid coated bullet vs a coated bullet with a grease groove, my vel go up. Same bullet wt, but more bearing surface in the bullet with no groove. What does that tell me, higher pressures. A proper sized lead bullet seals the bore better, no gas leaks that may occur with jacketed. My theory, love to see real data though.

[Larry Gibson]

Appreciate all the offers of help, I sure could use some but I know many of you would if you could. Ran into a technological problem today......I always charge up the battery in the M43 PBL the night before testing so I plugged it in night before last. Would not hold a charge.......:sad: Pulled it out and the date I put on it when I last replaced it was May of '09 .......where does the time go? Anyways, have a new one ordered but won't be here till next Thursday.....

DGV

I've removed numerous stuck bullets, jacketed and cast, from barrels over the years. The cast has always been much easier to remove.

[unique]

One question for Larry. What are the BHN's for the lead bullets?

The following are my thoughts and experiences for the 357 Mag. The softer the lead the higher the expected pressure. Starting with a properly sized cast lead bullet and near max loads, my experience in 357 Mag shows crossover around BHN 18 meaning a cast lead with BHN > 18 will have pressure/velocity close to a copper jacketed bullet.

The reason is the lead bullet has a lower cofficient of friction than a copper jacketed but the higher BHN cast lead 'leaks' more gas than the lower BHN. The other parameter at work is the powder itself as it can burn non-linear as function of pressure. Soft lead -> better seal -> quicker powder burn.

Hypothetically speaking a perfect sized cast lead relative to the bore would have perfect seal. This is not the case in reality as there is always some amount of gas leak past the bullet. This parameter overrides the friction coefficient in many cases for the 357 Mag.

As you well know, there are no absolutes since ballistics parameters can vary & interact . Thank you for your time. effort, and resources in running these tests!

[Larry Gibson]

Yes there are absolutes, they are called the laws of physics. You can indeed vary the parameters but the results, even though they may be different, will still be within the laws of physics. If we really stop and think about it there are many "absolutes". The problem we have is many think there are no absolutes (that statement contradicts itself because it is an absolute statement in and of itself) which gives them a means of rationalizing their own concepts w/o adequate proof or a realization of what is actually occurring. How many times did your grammar teacher tell you the rule is; "Never is never the subject of a sentence". Well, in that sentence "never" IS the subject of the sentence. That contradicts the absolute. Rules are not laws. There are "exceptions to the rule" which lend the perception to some that "there are no absolutes". The fact is there are not exceptions to the laws of physics. At least not here on earth. Today we can not send astronauts to the Sun because they would burn up. The laws of physics tell us that. Perhaps they will figure how to get around that absolute by going at night......... :groner:

Seriously, I also would assume, at this stage, that a higher BHN cast bullet would give a higher pressure given the same load. However, if we use the same mould to cast bullets of various BHNs and then pressure test with the same load we introduce another variable.....the weights of the bullets will be different because of the different compositions of alloy. We could mitigate that by using a single alloy and heat treating the bullets to different BHNs. Should you wish to undertake that task let me know, perhaps we can arrange a test? Keep in mind a published psi is almost always an "average", just like published velocities. There is always an ES (Extreme Spread) of any single test. Multiple tests of the same load will also result in an ES of their averages of both psi and velocities. Many times small variations can make such a small change, if any, that the change will fall within the ES of the test and thus be meaningless.

The OP's question and what I am testing is if we simply substitute an equal weight cast bullet for a jacketed bullet will the pressure be higher or lower than the jacketed bullet load's pressure. When you see the results of the test you will see I use several different cast bullets of different alloys (BHNs) of equal or very close to equal weight in a couple of the cartridges. As to whether the change in bullets from jacketed to cast given the same load will be meaningful remains to be determined by actual testing instead of hypothesizing. I prefer to test to find what really occurs vs hypothesizing and think the results could prove interesting.....whatever the actual test results are.

[tazman]

Larry-- It sounds as if some people are trying to set up things with supposition, so they can claim your results are wrong or at least not realistic.
I will wait for the results and see what turns up. I have seen tests you have run before and I will accept your results.

[Larry Gibson]

Tazman

Does seem that way..no problem, just human nature. It's difficult to counter precepts we've come to believe......was for me anyway. In the last 12 to 15 years I've revised my thinking on a lot of things with cast and jacketed bullets from things I'd been led to believe as read in books and magazines. Actual testing has proven many of those precepts incorrect or blatantly false.

I've stabbed a lot of sacred cows on this forum and several others. Been banned on a couple including this one. It's unfortunate that some take it as a personal affront when we learn from actual test results that our preconceived concepts are not correct. As I said I had a real problem accepting some of it myself as I always thought the "famous" writers were the "experts" and what they said was written in stone.....right? Well I found out maybe not, maybe they weren't correct and their ideas were simply based more on assumptions than actual test results.

I've come to realize that admitting one's concepts are not correct per say based on results from actual thorough testing isn't a negative reflection on one's self, it's actually a positive reflection. Unfortunately some don't see it that way and refuse to consider anything that may contradict what they've stated or believe....and that's ok.....I've gotten used to it here and just keep trying to further explain what I've learned from factual test results. Sometimes it's accepted, many times not. Yes, I have changed my mind or modified my ideas on many things the last 12 - 15 years in this game. It's called ......learning.....

As I said I don't really know the answer to the OPs question. I am seeking to find the answer though. We shall see.

[unique]

Wow, I suggest something to consider for your test and get a blast of hot air running the gamut from laws of physics, my grammar teacher, something about a supposition, murdered cows, and what comes across as a need for understanding and empathy.

I sure got a lot to think about...

[JSnover]

I doubt hard cast would provide the same resistance as a copper jacketed bullet. Even if you got close I imagine there would be enough of a difference to get valid results.

[Larry Gibson]

Unique

All that was a conversation in general regarding numerous post. As I said I no longer mind the discussions. Yours was a specific question regarding BHN......a good question btw. It's one that may or may not be answered in my test. My current test will compare bullets of COWW against the much higher BHN Laser Cast bullets of the same weight/caliber/load. If that doesn't answer that question then a better test might be as mentioned?

[Mal Paso]

When 300 MP first came out, Alliant's load for the 240g Speer GDSP was 25g for 1570 fps from an 8 inch test barrel. I was getting a Lot less velocity than I expected even with a shorter barrel. Ben at Alliant suggested it might be because I was shooting cast. So I did a side by side test, same brass, same Fed 150 primer they used, in a 4" Ruger Redhawk. 6 shot strings.

The .431" 250g NOE 429421 ran 1306 fps

The 429" 240g Nosler JHP ran 1235 fps

The powder was out of it's useful range, but I'll bet on lead being faster. You would think lower pressure ...

[Walkingwolf]

From my own experience with lubed cast bullets is they use less powder for similar velocity, PC coated cast take even less powder. So I gather from their claims that less powder means more pressure.

[JBinMN]

I have the test rounds loaded. They are in;

357 magnum
44 Magnum
30-30
308W
45-70

There are 280 test rounds loaded in 28 tests. There are 14 loads with jacketed bullets and 14 identical loads with cast bullets. A couple of the cast bullets used weigh a few grains more than the jacketed counterpart but they are all close. A complete description of each load will be in the test result report. I will probably start a new thread with that test result.

That will take 8 - 10 hours of testing given; set up, shooting, target changing, entering data in the computer, barrel cleaning, the usual range interruptions, changing firearms, etc.. I am not sure I will get it all done in one test session. If not then each test of a given load with both jacketed and cast will be conducted back to back to keep the conditions as close to the same as that is the comparison we are looking at; the pressure difference between the same load with jacketed and cast bullets of equal weight.

Next I'll enter all the load data into the Oehler M43's program test format in the laptop (part of the system) I use at the range. I am watching the weather forecasts for a good day and potentially a good day following. I'll report back with the results when the test is complete.


Mr. Larry Gibson,

A similar subject was being discussed & I mentioned this topic & your posts here to be checked out for more info.
http://castboolits.gunloads.com/showthread.php?384203-Lead-vs-jacket

In re-reading this topic, I do not see the results of the testing, and I am thinking that you posted those results elsewhere in the forum, but am not sure. While I will search a bit to try to find those results, if you happen to see this post and can point me (& any others who might be searching) in the right direction to find those results, in case I don't find those results to post a link here to them, and as well in that other topic, I would appreciate it.
:)

[swheeler]

Yah, I didn't see the results either? Maybe they didn't come out like he supposed, so he never posted them!;-)

[Larry Gibson]

Yah, I didn't see the results either? Maybe they didn't come out like he supposed, so he never posted them!;-)

Nice try...........:roll:

Reason could be as simple as I haven't finished the test........:shock:

[swheeler]

I hear ya Larry, that old age slows a guy waaaaaaay down:kidding:

[JBinMN]

Nice try...........:roll:

Reason could be as simple as I haven't finished the test........:shock:

Thanks for clearing up my efforts to find the data& why I was not finding it.

G"Luck!, if ya ever get a chance to do the testing.
:)

Please post up what ya find if/when ya do.
:)

[Larry Gibson]

JBinMN

As you've seen on other topics I have posted results of recent and past tests. Those results have been what they were, not what I wanted them to be. I, like most everyone, fell for and believed a lot of myths, assumptions and theories proffered by supposed experts in the past and present. When many of those experts assumptions didn't work out I began learning, testing and discovering the facts. I made a lot of enemies but I also made a lot of friends but more importantly, I helped a lot of cast bullet shooters gain a better understanding of casting and shooting cast bullets.

I post the results of my tests. Some have proven my own concepts wrong yet I do post those contrary to someone's opinion. That's how I/we learn.

[waksupi]

JBinMN

As you've seen on other topics I have posted results of recent and past tests. Those results have been what they were, not what I wanted them to be. I, like most everyone, fell for and believed a lot of myths, assumptions and theories proffered by supposed experts in the past and present. When many of those experts assumptions didn't work out I began learning, testing and discovering the facts. I made a lot of enemies but I also made a lot of friends but more importantly, I helped a lot of cast bullet shooters gain a better understanding of casting and shooting cast bullets.

I post the results of my tests. Some have proven my own concepts wrong yet I do post those contrary to someone's opinion. That's how I/we learn.

Pretty hard to beat empirical data. Thanks for making it available.

[Messy bear]

I am not making any predictions. Western has some pressure barrels set up to mimic the free bore in a revolver (throat and gap and forcing cone). In straight wall cartridges, they have found that peak pressure mostly occurs before the bullet leaves the case.
And sometimes before much bullet movement.
In that senerio, it seems that a bullet that seals the case and NOT the barrel is going to develop more pressure. It will be interesting...

[303Guy]

Has anyone had the misfortune of a stuck jacketed bullet in a barrel? How about a stuck Lead alloy bullet? Which was easier to move?

Knocking or pushing out a lead boolit has the problem of expanding the boolit at its base as force is applied to it whereas a jacketed bullet does not do this. On the other hand, if the pressure of firing is high enough, the same could apply, except that the barrel gets expanded behind and partially up the length of the bullet/boolit by the gas pressure behind it. Hence the ability to measure pressure within the bore using strain gauges. This might explain the seemingly contradictory reports.

[swheeler]

Some day we will have the answer, guess it's just a waiting game now. Carry on

[DonH]

I did not read all posts in this thread but... Googled coefficient of friction and saw several tables showing coefficient of friction of various metals on other metals. The Western guy is correct: copper on steel is .23, lead on steel is .54. But then another site (engineering IIRC) showed LUBRICATED lead on steel... .14!!!
The guy should have done more research. We didn't know the numbers maybe but a fool knows lubrication changes things.

[303Guy]

There are many variable to take into account. I once fired some 218 Bee bullets in my hornet - .224 bullets in .223 groove bore with light charges. These shot erratically with some actually stopping in the bore. After a short while some of those would just drop out. They showed heat scorching. The jackets were expanding from heat, seizing the bullets in the bore. One of them was fired into a non-cotton fabric rag and actually melted the fabric to itself. There was no sign of pressure which would make sense since the bullets would enter the bore normally then heat up and stop without enough pressure to overcome the increased friction.

These bullets were also inaccurate with both light charges and full power loads, possibly due to the expanding jackets leaving the core loose within. Other .224 bullets shot just fine in this rifle.

Cast boolits could be exhibiting the same sort of behaviour. I would guess that harder alloys would show lower pressures than softer alloys under some conditions.

[DonH]

A simple test: .223 case, 55gr lead and jacket bullets, a fast powder and one rifle. Which bullet, lubed lead or jacketed will require the lowest minimum charge (think cat sneeze) to be expelled from the bore?

What is in play in (and maybe missing from) this discussion is that when a powder charge ignites behind a cast bullet launching it into a CONDITIONED bore the bullet obturates not against barrel steel but against the film of lube in the bore. Thuse the importance of the type of lube used. At low pressure anything that "greases" a bullet may suffice but the higher the pressure the more important the "film strength" becomes. Anhydrous lanolin is used in some lives but is also used in industrial drawing operations. It has great film strength. It is in my BPCR/Schuetzrn lube.
I have read and heard serious rimfire shooters talk of the importance of bore conditioning as in fouling shots after scrubbing a bore clean. Ruminating on this lead to my practice in my smokeless powder lead bullet rifles of not cleaning the bore down to bare steel, leaving some amount of lube film in the bore. My reasoning is that lube on a bullet lubes the bullet from it's grooves back and lubes the bore for the NEXT bullet fired. Given a good lube, the only bullet at risk of obturating against steel is the first shot from a thoroughly clean bore.

[Gohon]

My reasoning is that lube on a bullet lubes the bullet from it's grooves back and lubes the bore for the NEXT bullet fired.

Glen Fryxell gives a long explanation on what bullet lube really does. http://www.lasc.us/FryxellLubeCastBullets.htm One of the things he says is " In summary, bullet lube is pumped from the lube groove to the barrel surface by compression, linear acceleration and radial acceleration. In addition, lube is injected forward during the firing process, as the result of high-pressure gas leakage into the lube groove. This injection process forms a floating fluid gasket around the bullet, and serves to limit gas cutting and is a kind of ballistic stop-leak.".

Basically what he is saying is lube is formed around the entire length of the bullet...not just from the lube grooves rearward. Seems to make sense, otherwise the forward driving band would be smearing lead.

[KenH]

.....(snip)........ I've come to realize that admitting one's concepts are not correct per say based on results from actual thorough testing isn't a negative reflection on one's self, it's actually a positive reflection. Unfortunately some don't see it that way and refuse to consider anything that may contradict what they've stated or believe........ (snip).... Yes, I have changed my mind or modified my ideas on many things the last 12 - 15 years in this game. It's called ......learning.....
Larry, I couldn't have written a better explanation of my thinking - While I love to be right, I'm much more interested in the "correct" answer.

I'm looking forward to the results of your test.
Ken H>

[DougGuy]

I would venture to say it's like comparing apples to apples and oranges to oranges. All things being equal, the cast boolit would have less friction in the barrel, which would obviously lessen pressure in comparison to the J word.

HOWEVER.. If that cast boolit is hardcast, BHN22 and it uses that hard crayon lube, I could see where this boolit would present more resistance against swaging into the rifling, and more resistance against travel in the bore because the lube was hard and not really doing it's job, and so this boolit could raise pressures in comparison to a softer boolit with soft lube. I would figure a J word in the same weight range would fall somewhere between the two.

As far as which bullet/boolit raises pressures in comparison to the other one, the answer could go both ways depending on the boolit you use to compare.

[DonH]

Glen Fryxell gives a long explanation on what bullet lube really does. http://www.lasc.us/FryxellLubeCastBullets.htm One of the things he says is " In summary, bullet lube is pumped from the lube groove to the barrel surface by compression, linear acceleration and radial acceleration. In addition, lube is injected forward during the firing process, as the result of high-pressure gas leakage into the lube groove. This injection process forms a floating fluid gasket around the bullet, and serves to limit gas cutting and is a kind of ballistic stop-leak.".

Basically what he is saying is lube is formed around the entire length of the bullet...not just from the lube grooves rearward. Seems to make sense, otherwise the forward driving band would be smearing lead.

I do not dispute Fryxell but I am not sure how his theory can be proven. I do know that unless the bore is cleaned with harsh degreasers between shots each bullet fired conditions the bore for the next one. I could be wrong as to the reason but my practice works.��

[303Guy]

I would venture to say it's like comparing apples to apples and oranges to oranges. All things being equal, the cast boolit would have less friction in the barrel, which would obviously lessen pressure in comparison to the J word.

HOWEVER.. If that cast boolit is hardcast, BHN22 and it uses that hard crayon lube, I could see where this boolit would present more resistance against swaging into the rifling, and more resistance against travel in the bore because the lube was hard and not really doing it's job, and so this boolit could raise pressures in comparison to a softer boolit with soft lube. I would figure a J word in the same weight range would fall somewhere between the two.

As far as which bullet/boolit raises pressures in comparison to the other one, the answer could go both ways depending on the boolit you use to compare.
I lean the other way. I suggest that the harder alloy boolit will give less resistance in the bore. More initial resistance in the throat but less in the bore. That being due to having more strength to resist upset and exert pressure against the bore. So it would depend on each circumstance.

[OS OK]

Let me state a few things that I am assuming....

*The easier it is to push a projectile down the bore...the less pressure in ft/lbs of energy is required to move it along inch for inch.

*The projectile that moves easiest...travels farthest in the barrel within any given time and creates the most volumetric space behind it at a lower pressure.

*The more volumetric space there is, the less the pressure can build to a maximum before the projectile leaves the barrel and uncorks the pressure vessel...the increasing pressure is expanding into an ever increasing space...all this in such a little time frame that it boggles my mind, too many thoughts going in too many directions and I end up fogged.

__________________________________________________ __________________________________________________ _________________________________

I read this years ago in an article in Speer and have tried to reflect on the events here but this is about pressures in a rifle and prolly a proof round to boot.
Anyway, I thought it worth mentioning as the first few milliseconds are prolly relative though the powders have a wide difference in burn rate.

This following 'interpretation' is from an article published in "SPEER, Manual #7 for Reloading Ammunition", pub. 1966-7. author; DR. Edgar L. Eichhorn

I had to read it several times endeavoring to understand exactly what happens in this 'Internal Ballistics' subject as it was different than I'd imagined. Another problem for me was this event all took place in 1.35 milliseconds, .00135 second, 135/100,000's second.




The 'Pyrostatic Epoch' begins with 'primer ignition'
elapsed time (et.) 5/100,000's second
the boolit is just this instant going to 'START' to move, but it has not
6,000 lbs./sq.in. pressure develops, the brass swells in chamber and seals it
4,000º F. temperature/in chamber
3 1/2% of powder charge is consumed

The tip of the boolit has traveled 1 inch, is now fully in lands/grooves and engraved, acceleration has begun
et. 40/100,000's second
70,000 lbs./sq.in. and pressure is now at maximum
3,470º F. temperature in barrel
38% of powder charge is consumed
1,000 FPS Velocity and climbing
681.8 MPH and heading toward the sound barrior [ V x FPS x .6818 = MPH ] {this my extrapolation, hope it is correct.)

The boolit has traveled 9 inches and the 'Propulsive Epoch' has ended
et. 75/100,000's second
24,000 lbs./sq. in. pressure and is in 'decline' as the accelerating boolit is making more volume behind it than the 'hi-pressure gasses' are able to fill.
2,300º F. also in decline
100% of charge is consumed
2,200 FPS Velocity and climbing as it is under 'Hot expanded gas propulsion' only, from here on out
1,499 MPH has broken the sound barrier and continues to climb

The boolit is exiting the 27 in. barrel
et. 135/100,000's second…1.35 millisecond… .00135s
6,000 lbs./sq. in. remaining pressure flashes into atmosphere and is luminous to the eye…
1,490º F. gasses and powder and lube smoke fill the air...
2,700 FPS Velocity and this now is in decline
1,840 MPH and when it travels downrange aprox. 900 yards, it will again cross back through the sound barrier where its RPM will be a critical factor in flight.
162,000 RPM as it emerges from this 1:12 twist barrel [ ((12/T) x V)60)=RPM ]…short version > [ (V x 720)/T = RPM ]…T=twist, V=velocity

"So how does this have anything to do with pressure differences questioned in this post? I haven't a clue, just thought I'd throw it in the mix and give Ya's something more to chew on."

[swheeler]

http://castboolits.gunloads.com/showthread.php?238516-Lead-bullet-pressures-are-greater-than-jacket-bullet-pressures-of-the-same-weight/page9

I have found dozens, if not hundreds, of examples of empirical data like this shot in real ballistics labs. You will notice that both are loaded to same OAL(HOW WE WOULD USE THIS DATA IN REAL LIFE), max charge for 230 FMJ 5.6grs and 19.7k psi, 230 Lead RN max charge 4.9 grs and 20.1k psi. Wow .7 grs more powder is a LOT in the 45 ACP case. If one used the starting load for FMJ to load that lead bullet you are close to +P pmax

[JBinMN]

Something to always remember is the length of the projectile itself & how deep into the case the Lead boolit is, vs the Jacketed bullet.

If the Jacketed bullet is .3" long & the Lead one is .4" long but the OAL is 1.20" for both, the Lead boolit when seated to that 1.20" OAL will be taking up more space(volume) inside the case than the Jacketed one, since the Lead one is longer than the Jacketed projectile even though both are the same weight. The remaining length of the round from the base of the projectile to the head of the case ( In this hypothetical .8" for the Lead while .9" for the jacketed) and thus, the volume inside for the Lead boolit would be smaller & thus allow for more pressure than the jacketed bullet would have. That would also be the reason for the difference in the powder amounts used. Less powder is needed for the Lead boolit since the powder & the resulting hot gases have less space to expand, the pressure will build faster than with the Jacketed bullet that has more space(volume) in the same size case.

The reduction in powder amount is to keep the pressure in a "safe zone" for each type of projectile in the same case, to prevent over pressures, so of course they can be different even though the rest of the data/components appear the same. ( case type/mnfr, OAL, projectile weight, etc.).

So, just using the comparison of the two, without taking into account that the remaining volume in a case is not going to be an accurate comparison. The remaining volume in the case when the two are seated is not supplied & is likely the reason for the difference in pressures between the two projectiles.

[swheeler]

You don't know how much bullet is in the case because they don't publish the "lead' bullet used, it and the FMJ could very well have the exact same seating depth, actually the lead bullet could likely have less inside the case! I wonder if Johan loubster is still at Accurate

[OS OK]

That is just 'starting pressure' from only a %'age of the powder being ignited, when the projectile starts to move that volume behind the projectile increases and that changes the volume and pressure increase until all the powder is consumed and pressure reaches maximum.

[shdwlkr]

maybe this question has already been answered and I just missed it.
Is there any difference in resistant of a lubed vs jacketed bullet? what if the lead bullet is powder coated?
I understand a lot of physics, just have not solved the resistant question

[JBinMN]

You don't know how much bullet is in the case because they don't publish the "lead' bullet used, it and the FMJ could very well have the exact same seating depth, actually the lead bullet could likely have less inside the case! I wonder if Johan loubster is still at Accurate

Yes, they "could be" the same length, or likewise, they "could be" not the same length.

Let us consider the odds a little bit.

What is the likelihood that the length of the Lead ones are the same as the Jacketed ones, Verses the likelihood that they are the same length for all the different combinations of Lead boolits & Jacketed bullets?

My bet would be that there are more differences between lengths than ones that are the same in length.

I am not trying to argue, BTW, just pointing out something that some that read here may not have taken into consideration. ( I don't remember exactly but someone mentioned this same thing some time back. I think it was Mr. Gibson, but it may have been someone else.)

Anyway, in that other related forum topic I mentioned in a post a short time back, it seems that some folks are OK with using data that is for Jacketed bullets in place of data for Lead boolits. The consideration of just where in the case the base of the same weight projectile is "highly important" for safety reasons, and thus it IMO, it has a lot of bearing on this discussion as well. If the volume remaining in the case when the projectile is seated is different than one another, then the results of any experiments will not be accurate as a comparison.

So, I was trying to point that out in the last post, that while the OAL is the same & the projectile weight is the same, the volume in the cases being compared may not be the same, so the powder amounts & pressures will not be the same.

"All things are Not Equal" for good comparisons so far & isolation of all the factors we are talking about, except Lead vs Jacketed. would need to be tested to find out, so until someone testes with all things the same, but for the difference of Lead vs Jacketed projectiles, we will not have the correct answer, but only supposition about what the correct answer might be.

We need to have projectiles that are the same in caliber, weight, powder amount, primer, case, etc., and the OAL should not be as important as having the base of each type of projectile be seated to leave the volume in the case the same. Remove all differences in variables that have an effect on the projectiles travel thru barrels of the same length with the exception in type of materials used to make the projectiles.

Until then, or until someone can show us all where such testing has been done, I don't think there is anything else, but hypothesis being presented with no proof to prove anything for a definite answer.

[Jeffjmr]

I don't really have a dog in this fight, but I will share my thoughts. Personally, ALL ELSE BEING EQUAL (which it only is sometimes) I freely use target load jacketed data for starting points for lead loads after running it through Quickload.

I think part of the problem is getting married to the theory that if velocity goes up, pressure must have gone up. You can test this theory easily if you have a HP-optional mold. Cast one boolit with the HP, the other without. The one without the HP will be heavier. Load them identically. Shoot over a chrony. The lighter bullet, same load, same OAL, same driving bands same lube will be faster. Do you really think the bullet that got out of the case easier and required less force to accelerate down the barrel produced higher max pressure?

There are simply too many variables to make a rule that lead makes more pressure than jacketed. Powder burning rate, primer, bullet depth, leade, crimp, lead hardness, ad infinitum.

Another source of data that may lead some to believe lead makes more pressure as a rule, is the loading manuals for lead that list considerably lower max powder loads for the same weight lead versus jacketed bullets. But if you read the fine print, and also apply some logic, most recipes limit lead velocities to 2200fps or less. THAT is often why the max loads are so much lower than the jacketed. Pressures are not always listed for the lead loads but when they are be careful not to mix CUP and PSI. They only rarely coincide.

Lastly, bullet ogive shapes and bullet length sometimes limit OAL, and it is possible a lead bullet will need to be seated deeper than a jacketed bullet for chambering as well as magazine fitment. This could result in a higher peak pressure depending on the powder being used.

I use Quickload religiously. Often the velocities predicted by QL are phenomenally accurate. If someone uses QL and also has pressure test barrels, I would be very interested in knowing if QL's pressure estimates are as accurate. QL graphs bullet travel vs. time vs. pressure at millisecond granularity. It is very educational. I shoot mostly milsurp, so I keep predicted and/or known pressures well on the safe side.

My $.02, free for Prime day today.

Jeff

[swheeler]

I've learned patience is a virtue! Hey I've waited nearly 7 months for the empirical data, what's a few more months. It's all good, I have no doubt Larry will get around to it someday , carry on.

Maybe someday in the next few years?

[303Guy]

I pulled up this old thread while I was looking for jacketed loads using traditional cast boolit powders in rifles. So the issue of cast boolit pressure being higher or not than the same weight jacketed has still not been fully resolved or has it?

[Mal Paso]

Larry Gibson was on it and I think we got a partial result a couple months ago. Don't have a link.


If I remember correctly there was no consistent result and you could not depend on one being lower pressure than the other.

[JonB_in_Glencoe]

It's resolved as far as I'm concerned.
It is, unless it's not.

[midnight]

This is an older thread and I read most of it. After thirteen pages not much has been resolved. I occurred to me that powder coating has added another large group of variables to an already complex problem. I havn't seen any pressure tested data using powder coated bullets. I believe most of us treat powder coated bullets like traditionally lubed bullets, that is .001 to .002 over groove diameter. Is this necessary? It probably is since the coating is only .001 to .002 thick whereas a bullet's jacket is maybe .010 to .015 thick, sometimes even thicker. I jus thought I'd add a few more variables to the discussion.

Bob

[DougGuy]

Pressure occurs at a lot of places not just the initial curve. Magnum vs. standard primers, lot to lot variations in powder, PC as opposed to jacketed as opposed to cast, I would think boolit hardness would be one of the bigger factors, especially if cylinder throats are undresized, I don't think there is a common denominator in any of the pressure calculations.

You take each load and each gun, you figure out what to look for and you try some loads. Mostly they will all work if you are using published data like a loading manual, and you have signs you can look for if the load seems stiff in recoil, in almost any scenario, it will be the COMBINATION of things that cause over pressure signs.

I don't think there is much science in searching for a cast vs. PC vs. jacketed set of definitive answers since all that depends on so many other things.

[kreuzlover]

Western Powders are full of bovine excrement! All I got to say on the subject.

[fredj338]

Lead bullets can show higher pressures, just depends on the alloy & bullet design. A bullet with lube grooves will have less pressures than a solid bullet. this is easily proved over a chrono. There is a reason that substituting a lead bullet for a jacketed bullet raises vel, pressures a re going up. It would be nice if someone with a pressure trace would confirm all this.

[charlie b]

If you go back and read Gibson's posts on the subject. He has run pressure traces. Results are what was stated above. Sometimes jacketed are higher, sometimes cast.

Velocity does not always track pressure peak. You can have higher velocity at lower peak pressure if the pressure curve is 'flatter'.

[303Guy]

I was reading what someone wrote on the subject a few days ago and he was claiming that cast causes higher pressure. His reasoning was that less powder giving higher velocity with cast proved the point. I thought, "no it doesn't - it indicates less friction hence less powder and pressure to achieve the same velocity". But of course, that would be a wrong assumption too. It could mean that but it could also mean higher pressure. Only a chronograph used in conjunction with pressure trace equipment can say for sure. But it is an interesting topic. Thing is, at high load levels, strange things can happen like for example in a revolver, it is possible that the pressure as the boolit leaves crosses the forcing cone can bump the boolit up in the forcing cone causing a pressure spike.

What I found curious was the difference between a gas check boolit and a plain base bullet of the same design and weight.