AR feeding problems

[shibbershabber]

AR Pistol
5.56
carbine gas system

no ejection. Sent back under warranty, claimed defective gas block. Repaired and sent back.

took it out this weekend, first few rounds were fine but didn't get through a magazine without issues.

what its doing now is this:

ejects spent case
bolt stops against live round .

round is at an angle with bullet pointing at chamber and bottom of the case on magazine with bolt against the side of the case.

almost as if the bolt takes the round out of the mag but then runs over it.

brand new gun, no used pieces.

only had wolf ammo, which I have used well over 5k rounds in various ARs without issue.

no signs of anything on the cases... Not sure what's up.

there were times I could get a dozen shots off consecutively but other times it would jam every few times. I shot 120 rounds.

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[shibbershabber]

forgive the crude drawing, it was too bright to get a good picture.

you get the idea though

 

[MasterChief]

What kind of mag are you using?

5.56 and not .223 wylde?

 

[shibbershabber]

pmags

definitely 556

 

[MasterChief]

Gas block too open?....where were the casings ejected when running properly

 

[shibbershabber]

they were behind and to the right

 

[Medic!]

Same as any semi auto gun.

Try different ammo.
Try different magazines.

 

[F2CMaDMaXX]

Nice drawing

You need to look up bolt over-riding mag or round, it's basically not going back far enough, if they already messed with the gas block, i'd put money on it leaking and not sending enough back through the system.

 

[DirectDrive]

I'm not an AR pistol guy, but you said you are carbine gassed.
So your dwell is shorter than with pistol gas.
You said you are using Wolf ammo.
I would try some full power Lake City ammo like XM193 or M855.

My theory is that maybe the Wolf ammo combined with a carbine gassed pistol doesn't have enough power to fully cycle the BCG.

I would also try a known-good USGI mag. The way the top cartridge "presents" (read feed lips) and how fast it comes up (read spring strength or sticky follower) could be an issue.
Change one thing at a time so you can track what's going on.

 

[MilitantBEEMER]

One of my buddies had the same problem with his, we pulled a lighter weight BCG from one of my rifles and it ran fine. Turned out he was not getting enough gas,had the gas block opened up and that solved the problem.

 

[partsed]

Interesting as our family was at Tritac yesterday and my sons AR did virtually the same on the range. I was able pull the bolt back with charging handle (eventually), but the round was jammed in (for the lack of a better word) channel/spline/groove that the bolt marries into when it is forward. Ended up getting one the guys to come in and look at it and he was able to get the magazine out (we couldn't-Hexmag magazine) and pop the round out of the ejection port.

 

[partsed]

The kid put his magazine back in and no problems after that. The guy told him it was just a strange coincidence that the round wedged itself in the groove.

 

[shibbershabber]

interesting.

i was able to pull the CH back a little and it would chamber & fire okay.

 

[MasterChief]

Lube it up, use diff ammo & mags.....be safe!

 

[dmack]

Also check the gas key on top of the bolt carrier. Sometimes they aren't staked and come loose, causing he carrier to short stroke. Broken/missing gas rings and a missing gas tube pin can cause it too.

 

[MasterChief]

Gas rings have gotten me twice! good call dmack.....

 

[shibbershabber]

how can I tell on the rings?

the bcg is new, could they be out of spec?


next time ill take my other bcgs out too


I love this thing... Really want it to work out

 

[v0lcom13sn0w]

is this steel cased ammo? could be the whole problem

 

[v0lcom13sn0w]

you can check gas rings by taking the bolt out of the carrier and doing a visual inspect. sometimes i like to take the bolt carrier group out and with leaving everything together i will pull on the bolt which extends/rotates it forward then stand it up on the bolt face, if it doesn't collapse into the carrier then your rings are most likely OK.

 

[diagoras]

If it's short-stroking you should be able to see it doing it, by shooting a video and then running it slo-mo.