Normal or is something wrong

Discussion in 'The Ammo & Reloading Forum' started by Jackman, Jan 29, 2011.

  1. Jackman

    Jackman Member

    Jan 12, 2008
    Ive been shooting my vintage 1911 with store bought ammo I have noticed that some of the shell cases after being fired have a very very slight bulge at the base, normal or a sign of a worn 1911?
  2. LDBennett

    LDBennett Well-Known Member

    Dec 20, 2003
    Hesperia, CA
    It is pretty common for the case to bulge just in front of the rim of a 45 ACP case that gets shot in a 1911. It is no problem if you shoot 45ACP cartridges that are at industry standard levels, assuming the gun has not been modified from the factory condition.

    It is caused by the feed ramp intruding into the spaces of the chamber. Pull the barrel out of the slide then drop a case into the chamber. The throating and the ramp on the bottom of the chamber leave part of the case exposed (on the bottom of the chamber) in almost all modern 1911's. The cartridge case is a gasket for the tens of thousands of pounds of pressure generated by the burning powder. The brass case is suppose to deform and seal the chamber and that pressure is everywhere inside the case. The case over the feed ramp, being unsupported, expands somewhat to stretch and ballon into that unsupported space. Normally the brass is tough enough to just barely bulge IF the throating and feed ramp are not too overdone. Get it wrong or fire too hot of a load and the bulge ruptures.

    John Browning designed the 1911 to feed only one type of ammo... the FMJ ball ammo he designed for the military. After WWII some gunsmiths tried to make the 1911 into the do-all gun, shooting every imaginable bullet shape other than FMJ ball. To get the gun to feed, they throated the end of the barrel and adjusted the feed ramp leaving the case unsupported near the feed ramp. This has migrated into almost every new 1911 sold today because shooters want to shoot 45ACP rounds other than ball FMJ, like hollow points and even semi wad cutters.

    There are some new 1911 that don't follow the originals feed ramping and throating and have a real feed ramp on the end of the barrel. The chamber is fully supported but the 1911 frame that uses this style barrel has to be different than John Browning's original 1911 frame.


  3. noylj

    noylj Active Member

    Jul 27, 2007
    Never happened with any of my 1911s. This does happen when someone over-polishes the feed ramp or lowered the ramp in an attempt to increase reliability.
    I would have it looked at by a gunsmith. The .45ACP is a very low pressure round and you shouldn't be getting "Glocked" brass from any non-plus-P .45ACP loaded to SAAMI pressure levels.
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