I have a keyhole marked 14.5" flattop upper on a Bushmaster lower. I've been having an issue with brass extracting but going completely ass over tea kettle in the breech, not ejecting and getting jammed up with the next one. It earlier had an over-bolt stoppage, something I had never seen before. It failed the standing BCG test, so I replaced the gas rings on the bolt and throughly re-cleaned and oiled everything, including removing the extractor - there actually was a small foreign object in there. I was able to reduce the problem from 1 malfunction in every 2-3 shots, down to about 1 in every 5-6 shots, a marginal improvement, but not a solution. I was using a 5/30 PMag and a 5/30 IWI mag, shooting Federal/American Eagle 55gr FMJs. What am I missing?
Having an AR issue, any help would be appreciated
- Thread starter Paul_M
- Start date
It looks like you have an extraction problem. A cheap fix to try is to add a small O-ring to the extractor spring. This is a know fix for short barrelled AR's that have extraction problems. Your local hardware store should be able to fix you up. IIRC, the o-ring size is 1/8" OD, 1/16" ID. It's probably the smallest size your hardware store carries.
It looks like you have an extraction problem. A cheap fix to try is to add a small O-ring to the extractor spring. This is a know fix for short barrelled AR's that have extraction problems. Your local hardware store should be able to fix you up. IIRC, the o-ring size is 1/8" OD, 1/16" ID. It's probably the smallest size your hardware store carries.
Keep in mind, most of those hardware store o-rings break down when exposed to heat and/or petroleum based oils etc. If anyone is looking for extractor o-rings, send me a PM.
I've had mine on two AR15's for 4+ years now. No sign of any breakdown or softening so far. Bought them at the local Home Hardware store. And I keep my ARs quite "wet" for proper functioning in any condition
brownells i think?
UPDATE: I installed a BCM extractor upgrade kit - spring, plug and o-ring. The ejection problem is definitely better than it was, but it hasn't solved the problem. It had been failing every 2-3 shots, now it's stovepiping about every 8 shots. What else could be causing this issue? I'm at a loss.
do you clean and scrub the chamber??? mine will do the same if I neglect to clean the chamber, the brass gets stuck and the next round jams up to the fired round and pushes the bullet into the round that's trying to load, if that makes sense.
Check the spring for the ejector plunger in the bolt, it may have broken or fatigued. Remove the bolt and hook and empty brass under the extractor and tilt it in flat against the bolt face compressing the ejector, you should feel the spring pressure and when you release the brass it should flick it out (point it away from your face and away from anything fragile).
How many rounds through your carbine?
Do you have a carbine or rifle receiver extension and receiver?
What type of buffer tube do you have carbine or rifle.
Is your spring length correct?
What type of bolt carrier do you have?
Colt non shrouded 1/2 circle carrier 8.63oz
Colt shrouded 1/2 circle carrier 8.87oz
Bushmaster non shrouded AR15 carrier 8.92oz.
Bushmaster shrouded AR15 carrier 9.26oz.
CMT M16 carrier 9.46oz
What buffer weight are you running?
Carbine buffer 3oz.
H1 Buffer 3.7oz
H2 Buffer 4.6oz
H3 Buffer 5.6oz
A1/A2 Rifle 5.1oz
Do you have a carbine or rifle receiver extension and receiver?
What type of buffer tube do you have carbine or rifle.
Is your spring length correct?
What type of bolt carrier do you have?
Colt non shrouded 1/2 circle carrier 8.63oz
Colt shrouded 1/2 circle carrier 8.87oz
Bushmaster non shrouded AR15 carrier 8.92oz.
Bushmaster shrouded AR15 carrier 9.26oz.
CMT M16 carrier 9.46oz
What buffer weight are you running?
Carbine buffer 3oz.
H1 Buffer 3.7oz
H2 Buffer 4.6oz
H3 Buffer 5.6oz
A1/A2 Rifle 5.1oz
It is possible, but it is also possible that he has a spring that is too long or short, using a lighter semi auto carrier, and too light a buffer screwing up the timing.
UPDATE:
I swapped out the gas rings and installed an enhanced extractor, no solution... then I swapped out the buffer spring, on the assumption that the old one was worn out, and replaced it with a new carbine length spring. That made the problem worse somehow - it failed every shot with Pmags and every few shots with LAR-15 mags. So...maybe a carbine length spring wasn't the right one, but it's a 14.5" upper sitting on a Bushy XM-15-E2S lower, so I think it does need the shorter spring. The issue is the same as before - the spent brass is extracted but rotates up to 180 degrees in the breech and doesn't get ejected, then it strips another round and everything gets jammed up.
So now, by little more than the process of elimination, I'm going on the assumption that it's overgassing and everything is just happening too quickly in the breech, so I'm thinking of replacing what I believe is a standard weight buffer with an extra-heavy one, around 5.5oz. It's the last thing I can think of. I have a hunch that the solution is probably pretty simple...and it's out there somewhere. Thoughts?
I swapped out the gas rings and installed an enhanced extractor, no solution... then I swapped out the buffer spring, on the assumption that the old one was worn out, and replaced it with a new carbine length spring. That made the problem worse somehow - it failed every shot with Pmags and every few shots with LAR-15 mags. So...maybe a carbine length spring wasn't the right one, but it's a 14.5" upper sitting on a Bushy XM-15-E2S lower, so I think it does need the shorter spring. The issue is the same as before - the spent brass is extracted but rotates up to 180 degrees in the breech and doesn't get ejected, then it strips another round and everything gets jammed up.
So now, by little more than the process of elimination, I'm going on the assumption that it's overgassing and everything is just happening too quickly in the breech, so I'm thinking of replacing what I believe is a standard weight buffer with an extra-heavy one, around 5.5oz. It's the last thing I can think of. I have a hunch that the solution is probably pretty simple...and it's out there somewhere. Thoughts?
adjustable gas block, see my post above
