Quote:
Originally Posted by Slamfire
High pressure can and does cause a huge number of problems. Blown case heads were rather common in S&W 40's. Blown primers that get lodged in the mechanism. Notice the trend to crimp primers on everything?, because primers are coming out and jamming the mechanism. Failure to feed, where the slide jams on the middle on the top cartridge because it was moving too fast. Failures to eject, the rim gets ripped off. Cartridges that are operating at the top of a pressure envelope are very sensitive to increased temperatures, case construction, changes in seating depth, case protrusion, etc. You will have fewer problems if you can do the same job at a lower pressure.
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The 40 S&W blowout were a problem in Glocks in which the barrels offered little case support, so it's not a +P pressure problem in that case. It's a problem with proper case support and weak brass with standard pressure ammo.
https://thefiringline.com/forums/new...reply&t=593147
If primers are blown out of the case in a pistol round, you're way hell above +P operating pressures, into the land of excess rifle pressures, or have crappy headspace. According to this source (
https://squibloads.wordpress.com/rel...the-crimp-out/), the primers are crimped in military ammo to keep the primer in place in barrels that can have loose headspace. And to help keep them in place during rough transport over long periods of time. See this:
https://www.thehighroad.org/index.ph...ockets.618616/ And this:
https://www.quora.com/What-are-crimped-primers And this
https://detroitammoco.com/removing-p...pocket-crimps/
If high pressure itself was a cause of blowing primers out of the case, then every cartridge above XX,XXX (select your limit) pressure would be blowing out primers all the time. Yet many cartridges have very high pressure limits, such as the 9X23 Winchester (55,000 psi), 221 Remington Fireball (60,000 psi), 327 Federal Magnum (45,000 psi), 356 TSW (50,000 psi), 357 SIG (40,000 psi), 454 Casull (65,000 psi), 460 S&W (65,000 psi), and 500 S&W (60,000 psi), and that's just handguns rounds. Rifle round are routinely 55,000+ psi.
Rarely does commercial ammo have crimped primers. The handgun rounds that have it are almost always military surplus, like the 9mm. In most military ammo, crimped primers are common, for the reason cited above.
Failures to feed as you describe are an issue with slide velocity, not chamber pressure itself. You can have those malfunctions from simply having a mismatched recoil spring, or weak magazine spring with standard pressure ammo. The rule here is to match how the gun is tuned to the recoil force of the ammo.
Quote:
Originally Posted by Slamfire
Cartridges that are operating at the top of a pressure envelope are very sensitive to increased temperatures, case construction, changes in seating depth, case protrusion, etc.
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We agree here.