last time out, case got stuck in chamber. hammered it out and cleaned well
went out today. went thru 80-100 rds flawless (except for rd 10 which i had a round halfawy extracted and the next live half fed) . after the 80-100 case stuck. extracted with heavy pull on charge handle. shot 2 more, stuck... extracted manually but extractor slipped off case with hard pull,, had to be hammered out. tired one more time, repeat jam.
i have recently switched to a 9mm buffer but i dont think that would cause this, if anything it would help.
16" LMT upper
bush lower/ m4 stock w/9mm buffer milspec CMT carbine spring
have to check gas key but it was tight before todays shoot, it is staked 3x ea
wolf 55gr polycoat
standard extractor, no o ring
visual inspection of brass, they are pretty clean. a little black residue on the case neck
i have a H and a carbine buffer at my disposal for testing, but i like the recoil with the 9mm
i have over 3,000-5,000 rds of wolf thru it. it is not just the paint coming off the ammo
think it might have been the extractor. had a bit of carbon built up under it. scraped it off with a razor and slapped a #60 o ring over the spring. hope that fixes it.
checked gas key and it is still tight
sounds good. just cleaned the chamber with some stronger stuff than i used last time. also used a chamber star for the lugs. got out alot of stuff. guess i missed it the last time
looks like i mangaed to sligtly scrape the area on the lug recess on the upper. looks like the bolt was 90% unlocked when i hammered it out the last time and it scraped. looks like it should still work. i will get a pic of if tommorow. thanks for the help
1. hose that chamber with some brake cleaner
2. use your favorite bore cleaner with the chamber brush and clean throughly
3. rinse out with brake cleaner
4. get behind the lugs with the chamber stars
5. lightly lube with your favorite oil
don't forget to clean your bore next in sequence. all the crud you rinsed out went down the barrel.
I think between your addition of the o-ring and cleaning the chamber you should have your problem whipped.
you're wasting too much money with chamber stars. get a hemostat and use the ends of q-tips to get behind the lockup portion of the barrel extension.
the chamber stars are pretty cheap. they last a long time, like a bore mop