Double Charges in Autopistol, Cont.

v35

September 03, 2012 20:51

The answer to your question is no.
Explosion rates are many thousands of feet per second, a lot faster than a slide will move, So you can still burst a blowback pistol barrel in addition to damaging the slide, ejector and slidestop with a gross overcharge.
There are no over pressure safety valves in any firearm save Mauser and Arisaka style rifles where a burst case can safely vent out a hole in the receiver ring without wrecking the gun.
Arisakas specifically addressed the blowup issue with safety breeching.

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  beantownshootah

  September 04, 2012 07:34

  quote:I have a question about reloading auto-loader rounds vs. revolver rounds. I have seen photos of what has happens to revolver cylinders after a double powder charge.
  
  My question is does this happen the same way in a blow-back operated auto-loader pistol if there is too much of a powder load? Will it just vent the excess gas during recoil?
  
  The quick answer is that since they are designed different autopistols will react differently to overcharged rounds than revolvers do.
  
  But no, blowback pistols will not safely bleed off extra gas from overpressure rounds.
  
  By design, pressure in blowback systems should peak before the chamber opens up. If you were to massively increase the pressure BEFORE the chamber opened up, you'd still potentially be subject to the same sorts of barrel failure you could see in any other system. Even if the barrel didn't fail, massively increased chamber pressure would greatly increase rearward velocity of the slide.
  
  That increased rearward slide velocity can still ruin the gun by slide/frame battering or hurt the shooter (ie you don't want a dislodged slide heading rearward at velocity towards your aiming eye. . .not cool).
  
  In general, exactly how a specific gun will respond to an overcharged round depends on the specific design of that gun (eg what kind of locking system it has, how supported are the cartridges within the chamber), etc, how much the overcharge is, and how quickly the pressure spikes.
  
  The response can vary from no externally visible damage, all the way to a gun exploding like a hand grenade and throwing off shrapnel over many yards, posing a risk to bystanders.
  
  In between there, you have things like barrels bulging and/or bursting, grip and or magazines being blown off gun from ruptured cases leaking gas, locking lugs cracked or damaged, etc.
  
  There used to be a term called "super face" which referred to the beards pistol competitors used to grow to hide the facial scars they incurred when their overloaded and/or fatigued-case .38 super rounds blew up in their faces. Ouch.
  
  Note that even in cases where there is externally visible damage to a gun, that doesn't mean that there was no damage. Metal fatigue can still be an issue, and a weakened gun subjected to overpressure rounds can then be subject to premature failure from subsequent use of NORMAL rounds, typically in the locking system.
  
  The classic example of this is the older style Beretta 92 guns that were subject to the rear slide firing off during shooting and hitting shooters in the face. Supposedly use of lots of high-pressure rounds caused metal fatigue in the aluminum frames, with the above-mentioned issues.
  
  Bottom line, like all guns, autopistols are designed to handle ammunition that operates within a certain pressure range. How much leeway you have to exceed that range depends on the exact system, but its limited. Meanwhile, a true double-charge will probably increase operating pressure to MORE than twice the standard pressure, and there are precious few guns that can handle it.

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