Repeatedly Chambering the Same Round

08 May

Recently at Utah Concealed, a forum member brought up something interesting:

What is commonly known, and is referenced in the report, is that continuous loading of the same round(s) will eventually create an excessive pressure situation as the projectile is driven deeper into the case due to repeated contact with the feed ramp under force. As a .45 ACP round operates in the 21,000 psi range, projectile set-back may not create an over-pressure problem. When the S&W .40 cartridge, which operates at the 31,700-33,600 psi levels, several thousandths of set-back could generate enough of a pressure spike needed to disassemble the pistol.

What is shown in the Utah Concealed post is that chambering one round seven times can set a bullet back about 12 thousandths of an inch deeper into the brass than it is when manufactured.  This is what leads to the pressure spike mentioned above.  If you carry a concealed weapon, or even shoot in general, please go read that forum post and look at the pictures!

It looks like I need to check my carry ammo to make sure that none of it is set-back too much.
1 Comment

Posted by on May 8, 2009 in Guns, Self Defense, Tech


One response to “Repeatedly Chambering the Same Round

  1. Tam

    May 9, 2009 at 5:27 am

    I’ll rarely chamber a round more than a couple of times before firing it.I’m sure most folks know this already, but if doing so is unavoidable for whatever reason, you can always use one of the other rounds in the mag as an exemplar to check for setback; discard if any is noticeable.


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