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

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/...allistics-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.

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.

{shaking head in disgust}

Gear

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)

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.

Quote:

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Originally Posted by 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/...allistics-lab/
Using jacketed bullet data with a lead bullet of the same weight will result in higher pressures, everything else being equal.

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

[smilie=b::not listening:

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

Larry Gibson

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?

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.

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.

Attachment 102410

Old wives tales will never die.

Rick

That's just silly.

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

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

I think they got it bassakwards;)

Maybe someone should tell them.

Quote:

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Originally Posted by 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/...allistics-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.

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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.

Sometime I just have to SMFH

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.

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.

Quote:

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Originally Posted by 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.

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Touche'

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

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.

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

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?

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.

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.

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

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

Quote:

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Originally Posted by 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.

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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???

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

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.

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?

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.

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)

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.

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.

Quote:

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Originally Posted by LynC2

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

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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??

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Originally Posted by JonB_in_Glencoe

All things CAN'T be equal !

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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.

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

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Originally Posted by 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.

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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.