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Had similar issue with my PSA premium which has about 700 rounds down range. The difference, happened after cleaning; greasing the BCG (lightly) then trying to load a round. I tried 4 times before I took the BGC and Charging handle back out, applied a generous amount of grease to the BCG. Loaded rounds smoothly afterwards.
I did notice a gouge in each casing that jammed/failed to feed.
Could the problem be that the tolerances are still very tight thus mandating extra grease (lube)? PSA has not returned calls nor emails so I go with a heavily greased BCG for now.
Kind of a bummer when all write ups and or videos show a "thin light" coating of oil or grease. I use high temp wheel bearing grease now by the way. The old trusty Hopped gun oil I use on my sidearms was too thin.
Thanks in advance, this is my first M4 which is mil-spec.
John
I believe this to be a common problem with mil-spec M4's. Probably part of the reason some people view the platform as unreliable. Most barrel-extensions are not properly profiled, which I have encountered. Only my Daniel Defense is done correctly on the factory guns I have, although I have seen others. Seems to be several sources of barrel extensions and some are done right, some are not. This is overcome with stiffer springs, more lube, and other bandaids...or properly profiling the barrel-extension.
This is how a barrel extension normally looks:
This is the result:
(or what OP describes, bullet in chamber, but the denting and scraping slowed BCG velocity so much that the extractor did not snap over the rim as it BARELY chambered)
This is how it needs to look to be reliable:
Notice how pretty my Daniel Defense barrel extension is? No way for anything to get dug into or hung up on that! Feeds like buttah!
A file and some patients can get you there.
Last edited by WS6; 03-27-14 at 05:46.
Hey thanks brother. What exactly am I filing? I am new to the AR15 community, still a lot to learn. Or, should I attempt to get PSA to repair the problem?
thanks again,
John
lol I can relate. 30 years as a Vol. Fire Fighter Heavy Tactical Rescue member, I too mix the spelling up.
Okay, So the two lower grooves (ramps) is the area to work with the dremel using the firm wool polishing Bob and some metal polish. I have used the red polishing stick from dremel when polishing the copper base of spent rounds prior to making them into necklaces for people (the 180gr HST has been a big hit). Should I use the same or maybe Menzerna medium cut compound?
Thanks,
John
I'd use a jewelry file or nail care kit or something. You're just breaking a corner that's gouging.
If its a factory BCM upper I would have them replace it first, if it happens with that one too then I start taking the jewelers files to it. Or just pick up a DD barrel or similar.
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