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

[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

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.

[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.