What Exactly Causes Stuck Cases?

As the title says....

What is the exact, technical cause of steel cases sticking in some AR15's

I've owned a handful of guns that exhibit this behavior. My first was a M&P15. Shoot a 100 rounds, and cases would stick every 5 rounds. I also had a CAI Golani (Galil knockoff) that did the same thing (although less often). On a few of the occasions, I had to soak the case in Kroil overnight and ram the sucker out with a steel cleaning rod.

My LMT MRP piston has never had a stuck case in the thousands of rounds through it. My PSA 20" DI build hasn't either. Both guns will exhibt the occasional short stroke and FTF, but no stuck cases.

Is it an out of spec chamber? (too tight, wrong headspacing) Or is it a hiccup in the timing of the gas system? (incorrectly gassed rifle causing the action to unlock too early, before the case has had a chance to cool and extract). Or a combination of both.

Stuck casings causes can be caused by numerous things like (but not limited to) bad ammunition, corroded ammunition, polymer & lacquer coated ammunition, soft brass casings, wrong ammunition (shooting 5.56 in a .223 chamber), chamber is too tight, rough chamber, out of spec chamber, dirty/fouled chamber, badly machined bolt, worn out barrel, worn or too weak buffer spring, gun is timing wrong, bad or fouled extraction system, etc.

CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123

According to most it's a lack of maintenance and lube

Also, a weak extractor spring and/or worn extractor can induce a fail to extract.

Copyright © 1996 - 2013 :: AR15.Com LLC :: All Rights Reserved.
Any use of this content without express written consent is prohibited.