What's Causing My Cases To Break In The Chamber
Posted 21 March 2006 - 08:18 PM
Posted 21 March 2006 - 08:32 PM
What type of ammo?????????
Is it a Kahr?????????
Posted 21 March 2006 - 08:43 PM
Posted 21 March 2006 - 11:27 PM
with the potential for a similar failure. Hot loads increase the velocity of the bolt assy. which is not a good thing.
If its not the brass its because the cartridge case is not properly supported by the wall of the chamber, and under pressure the thin wall of the case is stretched beyond its elastic limit causing split/rupture.
My experience has been that these failures occur mostly when the cartridge is fired when not fully seated, as opposed to occuring during recoil. The pressure time curve of .45 ACP like most pistol cartidges is very steep and
peak pressures dimish very rapidly.
So, why does the gun fire out of battery....
- dirt/foreign body in firing pin assy. causing firing pin to stick at times causing early ignition, not
helped by weak or worn out firing pin spring - if round coils are flattened with wear replace. Also
check to make sure hammer is not sticking.
- dirt/powder residue (especially unburnt powder) build up in chamber eventually causing cartridge to
stick when being fed into chamber & being ignited just before being fully seated. If your ruptures happen
more as you fire more this could be it.
- if additional cases look like they could have ruptured but didn't, you may have developed a chamber
problem, nicked, jugged, etc.
There are a couple of other possibilities, but a) ammo, dirt/fouling is most likely.
Posted 22 March 2006 - 07:12 AM
It may sound strange, but take a video camera to the range to capture the problem then you can play it back is slow motion to help determine when/if the round is firing out of chamber.
Posted 22 March 2006 - 07:26 AM
The video is a great idea as well! Or , if you shoot left handed like me, just keep your right eye open...
Posted 22 March 2006 - 09:22 AM
In my experience, this is most often caused by well used brass that originally had an axial crimp applied to the case at the base of the bullet. This creates a line about the case that is more prone to fracture. It's more likely to happen in the SMG because of the generous chamber dimensions as compared to the pistol.
If you are loading a lot of such brass, it’s time to retire it.
Posted 22 March 2006 - 07:30 PM
Posted 23 March 2006 - 12:45 PM
Posted 23 March 2006 - 07:56 PM
What brass is being used? I hear others mentions some brass like PMC or the Federal in the blue box (i think) are not the best brass to use.
Just wondering, would this issue with what you described, leave a bulge or any minor disfiguring to where it would NOT fit in the case gauge.
Posted 23 March 2006 - 08:20 PM
Posted 25 March 2006 - 04:41 PM
28 West Hurley. Took it out today and ran one 50 round drum, and two 30 round mags of factory Federal (red box) without the gun missing a beat. Then, ran a drum of 50, 230 gr FMJ reloads using 6.5 grs of Unique. I had two case separtions. Rather clean circular case separation just about midway on the case. I'm not sure how many times these cases have been reloaded, but it can't have been more than 2 or 3 times. I measured the spent brass, and all seem to within factory specs. The problem appears to be my reloads and the Federal brass, but I can't be sure.