Normal or is something wrong - The Firearms Forum

Jackman · 01-29-2011, 06:00 AM

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?

LDBennett · 01-29-2011, 08:44 AM

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.

LDBennett

noylj · 01-29-2011, 06:23 PM

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.

01-29-2011, 06:00 AM	#1
Jackman V.I.P. Member Join Date: Jan 2008 Posts: 446	Normal or is something wrong 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? -->

01-29-2011, 08:44 AM	#2
LDBennett Advanced Senior Member Join Date: Dec 2003 Location: Hesperia, CA Posts: 5,754	Re: Normal or is something wrong 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. LDBennett

01-29-2011, 06:23 PM	#3
noylj V.I.P. Member Join Date: Jul 2007 Posts: 116	Re: Normal or is something wrong 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.