Cast vs jacketed boolits of the same wt.

[Tom-ADC]

Why is it you see two different powder wt's for say in 45-70 300 gr bullets one load for Jacketed bullets and a different load for a cast bullet of the same wt?
I mean 300 grs is 300 grs right?

[fishhawk]

one word "friction" steve k

[winelover]

YES & NO! Cast boolets can be pushed faster (build up less pressure) than J-words, hence the discrepency.

Winelover

[Tom-ADC]

What I'm looking at is a 300 gr jacketed bullet uses 24.0 grs of 2400 but I don't see that powder used for a 300 gr cast bullet.
Just curious I always load per published data have for years but that question always bugged me as some of the loads uses jacketed bullets looked like something I'd like to try if it was listd for cast bullets.

[45-70 Chevroner]

Tom-ADC: What rifle are you wanting to shoot this load in? IMHO I don't think that load will be a problem in any of the rifles offered in that caliber. I have shot j-word bullet loads using cast boolits for many years. A cast boolit as fishhawk mentioned "friction" and weight is the proglem here. If you are using cast boolit ie. same weight as a j-bulllet and sized to the same diameter it will not build as much pressure as a j-bullet. I'm not a 2400 fan at all,I prefer unique and 5744 and a few others.

[r6487]

I am loading for a 77/44 suppressed gun with weights of 265 up to 310. Am shooting each from bench and chrono'ing to pick standardized loads I want to settle down with at around 1050 ft/sec. There is a world of difference between cast and jacketed bullets of the same weight.

[Tom-ADC]

Thinking of shooting them out of a Pedersoli Sharps 45-70 the boolits I have are gas checked but the f.p.s. isn't real high about 1400 with 300gr j-word bullet & 1124 with a 405 gr.

[45-70 Chevroner]

Your Pedersorli will handle 29,007 cup. If you are using a Lyman load manual notice that the 1873 Springfield shows a 24 to 30 gr. load of 2400 for the 300gr. j-bullet and on the page for the 1886 marlin shows a 21 to 24.6 gr. load of 2400 for a 400 gr. cast boolit with a high end pressure of 26,300 cup, and a 293 gr. cast boolit with a 24.4 to 30.5gr. load of 2400 with a high end pressure of 26,900 cup. I have not had much luck with the 300 gr. cast bullet in either of my 45-70 rifles one is a Pedersorli Rolling block the other is an original action sharps with a new barrel.

[Tom-ADC]

I have the 300 gr got a good buy so bought them, they are okay but I won't buy anymore, I doubt I'll shoot anything less then 405 once the 300's are gone.

I have a few different types of extra powder laying around and looking for a fun way to shoot it up, I love shooting the Sharps and when I get serious withy it I plan on feeding it nothing but BP.

[fredj338]

YES & NO! Cast boolets can be pushed faster (build up less pressure) than J-words, hence the discrepency.

Winelover
I have a hard time believing this. All things being equal, pressure=velocity. Less friction=less velocity,not more w/ the same powder charge. You see this in loading moly coazted bullets.
The Barnes manual shows this nicely as the bullet are identical w/ the only diff being the moly coating. You will need MORE powder to equal the pressure to give eaula vel. Look at loading data where pressures are shown. Lower powder charges w/ most lead bullets give HIGHER pressure for equiv vel. vs jacketed.
I think it's the slightly oversize, more maleable bullet sealing the bore better. This increases pressure, mostly on initial firning, then once the bullet gets going, it may be slightly easier to push down the bbl, but the initial higher pressure is why you need smaller powder charges to equal vel/pressure as jacketded. The less friction=higher vel just makes no sense unless you increase powder charges & that isnot the case as most data for lead decreases powder charges.
FWIW, I would be MORE concerned shooting the jacketed bullet w/ a light charge as there is the chance the jacket could stick in the bore & the lead core exit. This owuld be bad. Save the very light loads for lead bullets & use the jacketed for medium to full power loads.

[45-70 Chevroner]

I guess I have to agree with fredj338 but I think it depends on the amount of bearing surface of the boolit. ie. How long the boolit is. Conserning the Jacketed bullet seperating from the lead core I have only heard of that happening with half jackets and gas checks but I would not swear to it.

[fredj338]

I guess I have to agree with fredj338 but I think it depends on the amount of bearing surface of the boolit. ie. How long the boolit is. Conserning the Jacketed bullet seperating from the lead core I have only heard of that happening with half jackets and gas checks but I would not swear to it.

It depends a lot on the bearing surface, but the size of the SP/HP & wt of the core would have an affect on "pulling" the lead core out of the jackets. The old Speer 240grSWCJSP were a good candidate as the jacket was pretty much straight & the core could more easily slip out. I doubt it could happen w/ something like a 300grJHP, but I wouldn't risk it. Besides, shooting jacketed bullets @ 600-700fps seems so pointless.:veryconfu

[Tom-ADC]

I'm missing something here I'm not talking about shooting jacketed bullets but cast boolits, so its a moot point about jacket seperation.
I'd like to use up the extra powder I have pluse some 300 gr cast boolits, I see one of the powders ysed for jacketed bullets but when I look at the same wt boolit in cast I don't see the powder in question listed.
So can you use a cast boolit in place of a jacketed bullet for the same wt?

[1Shirt]

Bottom line is yes, you can use a cast over the same load by blt weight. You can also drive most cars at over 100 mph. Not a good idea for either one. Stay with recommended cast loads and you won't go wrong.
1Shirt!:coffeecom

[rockrat]

r6487, careful about shooting cast in your supressor, as the boolit lube will degrade performance. If you can disassemble it, all the better.

[fredj338]

So can you use a cast boolit in place of a jacketed bullet for the same wt?
In two words, it depends. If the jacketed charge wt isn't a max load, you can generally substitue w/ a slight increase in vel & pressure. I would NOT plug a lead bullet into a max load called for w/ a jacketed bullet. Example from Hogdon:
300 GR. CAST LFP Hodgdon H4895 .458" 2.465" 45.0 1326 14,400 CUP 51.0 1464 15,500 CUP
300 GR. SIE HP Hodgdon H4895 .458" 2.525" 58.0 1654 16,500 CUP 62.0C 1874 21,000 CUP
Notice the diff in charge wts vs vel vs pressures shown. I would NOT want to drop that lead bullet onto the 62gr charge except in a very sturdy 45-70.

[45-70 Chevroner]

Again I bow to fredj338 you never start a load of any kind with a max load. Safety here is the real issue.

[Tom-ADC]

Again I bow to fredj338 you never start a load of any kind with a max load. Safety here is the real issue.

Everything I looked at when giving this some thought was and the minimum recommmended load. Regardless of what I load I also start at minimum and work up BUT I never load at maximum period.

300gr jacketed bullet starting load 24.0 grs of 2400 max load 30.0
Now if I were going to try this I would start at the suggested load of 24.0 if it shot well I'd leave it alone, but never would I approach the max of 30.0

Personally I think I'm on the side of being safe.
BTW this is from Lymans47th edtion page 354 if you'd like to check it.

[fredj338]

Personally I think I'm on the side of being safe.
BTW this is from Lymans47th edtion page 354 if you'd like to check it.
Interesting that they post 2400 in w/ 300gr & 400gr jacketed but not lead. That is handgun data, for use in almost any rifle, I would think you will be fine.

[spqrzilla]

Cast bullets and jacketed bullets behave differently. That's the bottom line.

For that matter, jacketed bullets of different construction can behave differently and result in different peak pressures. You must be careful when substituting different types of jacketed bullets. I once made the mistake of substituting a 130 grain Barnes bullet atop the load I used for 140 grain Sierra's ( the latter being a cup-and-core constructed bullet ). The result of my mistake was peak pressures so high in the Barnes load that the brass showed the ejector slot in the bolt face.

One simply does not substitute cast bullets for jacketed in loading data nor vice versa.

[MtGun44]

I routinely substitute cast boolits in loads for jacketed, never ever having any untoward
effects. It is an absolute fact that lead-tin alloys have a much lower coefficient of
friction on lubricated steel than copper. Whether this works in the barrel, I am not sure,
but it seems like it does to me. I THINK (do not KNOW) that lead boolits slide down the
barrel easier than jacketed, making for higher velocity and at least no higher pressures
than the same load with jacketed.

The lead-tin friction on steel thing is why ALL high speed oil lubricated journal bearings are
at least lined with a tin-lead alloy. If the load is very high, the tin-lead can't be too thick or
it will deform over time. The low friction is utilized at startup when the bearing is in contact
with the crankshaft or axle (old RR wheels) - once the oil pressure is up and the speed is up
on the rotating part, no contact occurs until shutdown when the journal "lands" on the
bearing as the speed and lube pressure drop. Can't prove that this is exactly the same in
a barrel with a boolit and a waxy lube, but I believe it is likely to be very similar, not higher
friction than unlubed copper based jackets.

Do not even THINK about substituting a jacketed bullet into a lead boolit loading recipe, esp
a high pressure load, this WILL get you an overpressure load. Look at loading manuals and
you will routinely see LESS powder is permitted for a given wt bullet compared to the same
wt boolit.

Be safe and start low and work up, always. I know that a low load for a jacketed will be
even lower for a boolit, so that direction substitution is safe.

Bill

PS Thinking some more - there were a few extremely high powered supercharged military
aircraft engines in WW2 that switched to "silver" main bearings when the conventional ones
started failing at extreme War Emergency Power settings. May have been pure silver overlay
or a silver-tin-lead alloy that was strong enough to take the extreme strain. Might be a few
other oddball cases, but essentially all journal bearings are lined with tin-lead alloys.

[Tom-ADC]

My thoughts exactly.
I just sent Lyman an email asking this question, I figure no way could they list every load possible. We'll see if they answer.

[Tom-ADC]

Lyman response: I think this is fair as I didn't get right down and tell them the varibles, just as I asked a general question here.


Unfortunately there are too many variables to make a statement on whether or not this can be done. Issues such as caliber, bullet seating depth, powder type and powder speed can all effect the load.