Sti Trubor Blowd Up w Autocomp

[Braxton1]

On 3/13/2018 at 6:53 PM, 4n2t0 said:

I've yet to see any definitive proof that bullet setback can cause a catastrophic failure. It's a term that gets thrown around when people can't explain or understand how they f*#k3d up.

 

Not 9Major or SuperComp, but I was party to some pressure testing back when .40 S&W was experiencing failures like this.  It was found that reducing COAL by 0.030 ("set-back", if you will) DOUBLED pressures on some loads.  This was all with factory ammunition, so the powders used were probably not ones that reloaders have access to, but it does prove a point.  40 is very sensitive to COAL....

 

The setback that most were concerned about in this research wasn't "the cartridge hit the ramp once and pushed the bullet into the case".  We were finding a lot of cops who were unloading and reloading their duty guns on a daily basis.  They would use the same cartridge for this process every day.  Eventually, it would get shorter.

[Bakerjd]

On 12/27/2022 at 12:37 PM, Braxton1 said:

 

Not 9Major or SuperComp, but I was party to some pressure testing back when .40 S&W was experiencing failures like this.  It was found that reducing COAL by 0.030 ("set-back", if you will) DOUBLED pressures on some loads.  This was all with factory ammunition, so the powders used were probably not ones that reloaders have access to, but it does prove a point.  40 is very sensitive to COAL....

 

The setback that most were concerned about in this research wasn't "the cartridge hit the ramp once and pushed the bullet into the case".  We were finding a lot of cops who were unloading and reloading their duty guns on a daily basis.  They would use the same cartridge for this process every day.  Eventually, it would get shorter.

Yep. We sent a bunch of ammo out after having a M9 blow up when I was in the Navy. The same ammo got loaded into mags twice or 3 times a day, amd at least on round got chambered at the beginning of every shift. After some probably expensive testing the command came out with anew guidance that when we went for live fire training, usually about twice a month if we weren't out to sea all the ammo checked out had to be used at the range the next time we went. 

 

Now I don't know what the test results were or if they actually sent ammo out to be tested but that was what command pushed to us. Only for the 9mm though.