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Thoughts on Heat Treated Cast Bullets

3205 Views 2 Replies 2 Participants Last post by  Dixie Slugs
The trend that Elmer Keith started about 1925 on cast bullets continue today. Many others, like Veral Smith, added new concept along the way. Many of the early problems, like over penetation/poor tissue damage are now understood and corrected by larger Meplat Area.
There are a few problems still with us and this is what I will dicuss.
Many of the early revolvers had larger chamber throats and the expansion of the soft bullets swaging down cause no real problems. Elmer commented on this in 1955 "Sixguns". There are other examples of the chamber throats being undersize. These revolers may shoot jacketed bullets (which tend to be undersize), but with cast bullets the accuarcy is poor.
Many years ago, Caldwell with Speer, did some tests that should be standard reading. He was not satisfied that the vented barrels used to test revolver bullets gave a true picture with hard cast, that was becoming popular. He machined a solid single shot cylinder that fitted the frame, added a transducer, and started pressure tests. What he found was that there was a pressure spike that ran as high as 3000+ psi as the oversize hard bullets hit the forcing cone in the barrel and swaged down. A couple of years ago I saw a Bisley Ruger that let go and the position of the blown top strap was exactly like the photos Caldwell had.
So......What and why is all this important. We now have handguns of various calibers working a pressures unheard of years ago.
The rule Elmer set up years ago, still holds true. In the .357 Mag, the bulet size and chamber throat should be no more than.001" above groove diameter with this extra hard heat treated bullets. The .44 and .45 bullets and chamber throat should be no more that.002" above groove diameter. If the are larger than this, some thought should be given to a softer bullet alloy.
A simple test that will suprise you, is to put a hard cast heat treated bullet in the muzzle of you handgun and with a rubber hammer try to drive it in........that vs. a soft lead bullet.
Again, these are just thoughts for you to consider.......Regards, James
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I got 150lbs of dirty bees wax given to me today, I just have to go pick it up, then I will start doing a bit of experimenting with it. No testing done this weekend had to work at my regular job! I found a mold to cast 158gr RN 38special bullets with so will be able to include with tests in the future. You know I bet it would really surprise people to see how much pressures spike when those hard cast bullets hit the forcing cones. I have heat treated bullets with a brinell of 22/23 that when shot into milk jugs just make them slump abit but will destroy jacketed bullets. So you know if there that hard they will really run pressures up if too much oversized!
Excellent John! As I mentioned about the tests ran in 1972....we used the Energy Deposit of the (then) standard 158 gr roundnose .38 Special as a factor #1.00 and based all others on a % of that. The real surprise was when we tested the Energy Deposit of the standard .45 ACP 230 gr roundnose. Al Handcock re-swaged the existing roundnose bullet to a truncated cone nose. We refired the load........same hull, powder, primer, and firearm. Tha cavity was about doubled and the ED about 50% more. That was when I first began to realize the importance of meplat area........James
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