Help: under gassed or over gassed

[LRRPF52]

It worked


You removed a part


Then is stopped working


First off, I'm curious where you read/heard that the extractor o-ring was a "bad" thing? And secondly, why you didn't replace it when a previously working upper quit working?

Doesn't sound like a gassing issue to me in the least. You've greatly reduced the tension the extractor has on the case head and now a "normally" gassed load is jumping the "rim"
The loads that function, but don't lock back aren't accelerating the BCG enough for the extractor to jump out of the groove.

Something tells me that replacing the o-ring will fix most of your problems


ETA, for the record, MOST factory barreled ARs, regardless of the caliber, are over gassed, so they'll still work with some of the weaker factory loads. With my "cans" I've gone, ALMOST exclusives with adjustable gas blocks, to help with the increased back-pressure related to running a silencer

Funny how we never had these problems with early M4s shot in high volume, and then the KAC QD suppressor was introduced with the first SOPMOD kit, then you started seeing FTExtract issues quite often.

That’s where the O ring and D Fender came from. To put more extractor tension on the extractor as a band-aid for the cyclic rate being driven out of the ideal window of operation for reliable primary extraction.

There was at least one day where I ran 1100rds of M855 through my M4, no malfs at all. This was pre SOPMOD heavy barrel profiles, pre H and H2 buffers, pre M4 PIP.

Same with my Grendels. None of them have the O ring on the extractor. If I see the added O ring on a bolt, I remove it immediately.