I was doing consulting work in the 1990s designing power supplies. My father was chief engineer over 150 engineers and draftsmen in a military gun and vehicle company that did research and some production for Detroit arsenal and Rock Island arsenal.
My father and I were arguing about design since I was a little kid. I made a lot of money blowing up my power supply designs to learn the weak spot, and improving that. I started handloading in 1999 and within days I was trying to blow up guns. I tried every bullet and powder combination to the point of brass failure in 9mm.
My father was disgusted with me at first for blowing up guns. When I showed him how I documented the process he calmed down. He then showed me how to calculate the strength of my 45/70 handi rifle: hoop stress, Lame's thick walled formula, section modulus, pins in double shear, etc.
Knowing the Rockwell hardness of a steel and it's thickness, you would think I could predict the threshold of failure in the gun. But tables of steel strength are for static loads that grow. The one millisecond pressure spike in a chamber never gets it done. Guns typically take 50% more peak pressure to wreck than where they pencil out.
Thousands of overloads later [5 years later of buying carloads of guns at every gun show], I have seen a lot of patterns and can predict what will happen. I had a mechanical engineering professor tell me in college, "if the rocket blows up on the launch pad, you don't learn much." In blowing up gun, a slow gradual work up shows the threshold of failure. It also makes the primary failure easier to find. Blowing a gun up with some random overload will not reveal as much information. It is dangerous too.
With the 7.62x39mm I hoarded RP brass with the small primer thinking it would go 80k psi and the Win large brass would give up at 60k psi.
I was never able to reach pressures where the RP had an advantage.
The SKS rifles would blow the firing pin back out of the bolt assembly.
I gave up on overloading sks rifles... weaker than the brass.
I gave up on the CZ527 blowing pieces of the bolt face off. Tired of paying for bolts.
The Rem 700, Sav 110, Win 70, Mauser 98 are good rifles are far as the bolt and reciever strength go..... but if the case fails they blow extractor pieces at me. Still plenty good for work ups until extractor groove expansion threshold is reached.
The good rifles to overload are Ruger #1, Sav 219, Handi rifle, ext. A rifle way stronger than the brass, and when the brass blows, no rifle parts or brass pieces comes flying at me.
What did I accomplish between 2000 and 2005 blowing up guns? I wrote to all the load book publishers that said the CZ52 was stronger than the Tokarev. I could not blow up a tokarev. CZ52s blow up with factory ammo. So the load books changed. They reduced ALL loads. CZ52 and Tokarev.
