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The post on lead bullets raised a question that I think deserves its own thread.

Is there a risk to firing some jacketed bullets at the end of a shooting session where lead bullets have been used? We all know, I think, that this technique is pretty common--I've used it myself. In retrospect, though, it makes me wonder. If there's lead buildup in the barrel, usually near the chamber, what kind of pressure increases and wear risks are we running by pushing a much harder jacketed bullet into it at high velocity?

Although jacketed bullets are .451 vs .452 for the lead, I believe this is simply because the lead is softer and can deform to engage the rifling where the jacketed will not deform as much, so the overall effect is probably the same in terms of how deeply into the rifling the bullet goes...true? Then again, a lead bullet of the same weight requires less powder than a jacketed--the jacketed bullet has less resistance travelling down the barrel. Is this because of the difference in bullet diameter, or simply because of the softer nature of the lead bullet? What causes the increased resistance of lead bullets?

So what happens when the leading is pushed out by the jacketed bullet? Is it significantly different than what happens when a lead bullet goes down the same leaded barrel?

Well, lots of questions. I constantly amaze myself at how little I know!
 

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This is a question that needs to be answered by a laboratory with pressure testing equipment. I don't recall such a test being done. Perhaps another correspondent does, and can enlighten us.

In the absence of that, we have to fall back on experience. The technique of cleaning lead from a barrel with jacketed bullets has been recommended by people with a lot of experience for about a hundred years now, and I have never heard of any problems associated with it. I have been doing it for over thirty years, with nary a hint of high pressure.

Incidentally, it is well established by pressure testing that lead bullets generally develop less pressure than jacketed bullets with the same load, all else being equal. A typical example is Winchester data for the .44 Magnum with 296 powder and 240 grain bullets. With the lead bullet, 25 grains of powder develops 1560 fps at 37,500 cup, while with the jacketed bullet, 24 grains of powder develops 1430 fps at 38,000 cup.

Hopefully, someone can refer us to a scientifically conducted test that will settle the matter without conjecture.
 

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I've never heard of such a test ever being performed, so we might never know.

It might be interesting to check jacketed bullet velocity in a clean barrel versus a heavily leaded one. That's about all any of us are capable of doing.
 

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Good idea. I will put that on my "to do" list. Though "heavily leaded" is difficult to define. I have a Wilson match .45 barrel that leads pretty badly due to use of stainless brushes (before I learned that lesson). I will put a couple of hundred lead bullets through it and then chronograph, check primer condition, etc., compared to a clean barrel.
 

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I've got some gas checked SWCs that I tried without a gas check in my .38 Super. These things tumbled out of the barrel after 25 rounds and all signs of rifling were hidden under a heavy coating of lead. That would be my definition of heavy leading and I can cast a few of these and repeat the leading next time I'm bored.

After the first jacketed round was fired the pistol shot accurately again. At least until I leaded it up with another test load.

Shortly after that I discovered cast bullets need to be aged whether they're heat treated or not. Lucky for me I now know how to use my lab oven to age bullets in an hour.

My .45s really don't lead enough to worry about with any load. I've had no leading problems with any guns except this one Ed Brown .38 Super barrel, and it shows signs that using jacketed bullets to clean out lead has a big drawback: While some lead is shot out, small amounts seem to be nearly permanently imbedded in the barrel. This stuff is really hard to remove even with a Lewis lead remover.

I don't know if this would be true for any other barrel, as all of them react differently.
 

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Well, I went to the range last week to do the test, and the battery in the chronograph was dead. Got back out yesterday with a new battery, and the terminal came off the battery clip. One of these days, perhaps Murphy will rest long enough to do the test.
 

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I decided to go ahead and perform my own test after making sure I had enough batteries.

I specifically cast bullets for this test, casting them the night before wth no aging or hardening. I fired them in my .38 Super that's been so much trouble with cast bullets as of late.

At any rate, after 83 rounds the barel was so leaded that the bullets were tumbling. Let the test begin!

Velocities were then checked after loading a magazine with a former FMJ match load. This was a Winchester .356" FMJ bullet charged with 7.3 grains of accurate #5 and an OAL of 1.250". It normally averages around 1125 FPS.

The results shooting this load with that filthy barrel are as follows:

1105
1136
1121
1109
1125
1138
1136
1136
1129
1128

Max = 1138 Min = 1105 Average = 1126 Range = 33 St. Dev. = 11.01

The most that can be said is that the leading may have dropped the velocity 33 FPS, although 4th shot was nearly as low.

The barrel cleaned up easily afterwards with no need at all for extended soaking or the use of my Lewis Lead Remover.

If dangerous pressures were being generated, I'd have to believe there would have been a significant effect on the velocity or at least the primer appearance. None of the 10 cases fired showed no signs when thoroughly measured. Unfortunately I didn't think to save the first case fired, so I could only check the 10 fired from that magazine.

My guess is that the average shooter likely isn't capable of proving or disproving the safety issues of cleaning the barrel with jacketed rounds.

Personally, I'll continue to fire a few jacket bullets after an extended lead session (when I remember to bring some).

I'm not sure why the barrel didn't show anmy signs of the lead being "imbedded" in the barrel this time around. I'm going to guess it's spotless condition at the beginning of the test may have had something to do with it.

I'll also note that before firing the soft bullets, I had fired some 600 rounds of properly prepared cast bullets, so the barrel was plenty dirty.

Rereading the initial post, I have to say that lead bullets have LESS resistance than jacketed bullets, not more. That's why less powder is needed for the same jacketed bullet velocity.

My understanding is that the hardest cast bullet is still only 1/3 as hard as most any jacketed bullet.

[This message has been edited by Walking Point (edited 10-04-2001).]
 

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I am no gunsmith, nor do I play one on TV. But I used to shoot a lot of lead before Uncle Sam chipped in to help me out.

Shooting jacketed over lead really mashes/grinds/swages the lead in. It would be cool if it was to act like a snow plow and sweep it out, but it never did for me. If the lead wasn’t really jammed into the rifling before, it was after the jacketed ammo ran across it.

It made cleaning a real drag. Seemed like I was scrubbing for an hour past forever. I stopped the chasing the lead with jacketed and it was considerably easier to clean. Shooter Choice lead remover helps also.

Tom
AF Shooting Team
 

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Walking Point, thanks for the assist. Your results were completely consistent with my experience.

I have had the same experience as Tom, but it was after a few jacketed rounds, and was solved by more jacketed ammo. I guess it depends on the severity of the leading and the number of jacketed rounds.

In normal circumstances, after a few hundred rounds of lead, a magazine of jacketed bullets leaves the barrel apparently lead free. But I have had leading bad enough to require two magazines of jacketed. I use fairly hot Hydra-Shoks, which may help.

Interesting discussion. It is a pleasure to discuss such things with astute folks in search of verifyable answers.
 

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I nearly always shoot lead and coated or jacketed bullets together. I load a magazine with lead and a couple of rounds of jacketed. It prevents a build up of lead. I think that if the lead is built up then the jacketed bullets tend to iron it in more. This week I fired 100 rounds of lead and 100 rounds of coated bullets. There was no leading in my barrel. Sometimes I have a slight build up, but it is easily removed with a brass brush and lead remover.
Jerry
 
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