CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.
I did a stress analysis on a 45/70 handi rifle ~ 10 years ago. My father, the great gun designing chief engineer, helped me and a mechanical engineering professor helped me too.
I calculated the action pin in double sheer, the hoop stress on the chamber with Lame's formula, and the section modulus on cross sections of the breech face.
I concluded it was so much stronger than the brass that it did not matter.
Some people on line said I was not qualified, so I validated my calculations by working up to double the max published powder charge for a Ruger #1 45/70 [the highest published load I could find].
Reference loads:
1) "Loads for the 45/70" from the H.P.White laboratory via "American
Rifleman" 1950~1968 via "NRA Handloader's Guide" 1969 says:
405 gr Rem S.P., 17.5 gr Unique, 1286 fps, 25,240 pounds pressure, for 1886 Win
2) "Lyman's 47th" 1992 says:
400 gr cast, 16.5 gr Unique, 1286 fps, 27,000 cup, for 1886 Win
3) "Lyman's 47th" 1992 says:
385 cast gr cast, 17.5 gr Unique, 1411 fps, 38,500 cup, for Ruger #1
4) My handi rifle validation test: 38 gr Unique 405 gr cast... 87 kpsi [Quickload]
Still some doubted me. This is a lesson in life. If math and test data will not convince them, then what kind of person are you dealing with?
Years later it was published that the handi rifle was in the lever action level of strength, not the highest. We have some dumb stuff going on the the gun culture. We need more myth busters.
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So I saw an off brand [OEM Stevens] break action 410 at the guns show for $50.
I could see it had it where it counts, kid.
So with 45 Colt brass and CCI200 large rifle primers I worked up to a 454 Casull double load.
That was 40 gr H110 405 gr cast bullet 2.75" OAL.
I realize that is not a 454 OAL, but H110 will not compress much.
I reported that test a couple times to THR in 2004
http://www.thehighroad.org/showthread.php?t=99238
Here is the pic I posted in 2004
What does it all mean?
I have tried to blow up a lot of guns over the last 13 years.
Break action 410s with thick walls are about as strong as guns get.
That .48" chamber with .275" thick walls is a lot stronger than any 454 revolver with thin walls. Ruger may have specialty steel in that revolver that can go to 260 ksi, but revolvers with those thin chamber walls as strong as a thick walled 410.