11.5" FTF Issue

[Uffdaphil]

Sonuva... Just erased whole post. Second attempt:

My new factory BCM 11.5" upper with new LMT enhanced carrier/std bolt, H2 buffer, pistol extension, would fire first round and not load next. 55grn XM193 Federal. Mags functioned in other guns. Swapped in H1 buffer with no joy. From what I've read two contributors to feed failure are gas leaking from carrier key and extractor spring/o-ring. I installed a BCM spring upgrade and took out the o-ring but have not tried yet.

Iraqgunz, my most trusted source, swears by the enhanced carrier in his 11.5" SBR. But I think he is running an A5 Vltor buffer system. So my questions: Am I better off with a BCM bcg with pistol spring/buffer? Could I possibly need a heavier buffer than H2? If you use the enhanced carrier in a 11.5" pistol, what weight buffer is gtg?

Pic just to prettify post.

http://i150.photobucket.com/albums/s92/uffdaphil/imagejpg1-27.jpg (http://s150.photobucket.com/user/uffdaphil/media/imagejpg1-27.jpg.html)

[Gaspipeshooter]

Is it failing to feed, or failing to extract & eject the spent round?

[UWone77]

I basically had this same issue with the very first BCM upper I owned. Not enough gas from the gas port and had to be drilled out.

Obviously don't do that.... first did you check using it with another carrier? Lots of lube?

[Fathom_Arms]

First thing I would do is check and make sure the gas block is seated to the shoulder of the barrel.

Second thing you could do is remove all the fuzz off the end of a q-tip and stick it down the carrier gas key and see if there is any blockage. Sometimes when carriers are coated the junk coaters use to plug the holes gets sent to the back of the gas key. Seen it only once in my life. But, you never know!

[KevinBLC]

If this is a factory BCM upper, I'd just call'em and let them figure it out.

[Uffdaphil]

Thanks for the ideas. I'll get in another range session to narrow down the problem before I pester BCM. Or LMT if it is the carrier.

[camomike]

Is your GB pinned to the barrel? I had a buddy replace his gas tube on a set screw GB when he put the roll pin back in he canted the GB enough to cause short stroking.

[camomike]

Also try checking the rings on your bolt.

[okdonk]

I had the same issue and turned out my BCM BCG was leaking on the gas key.
Sent it to BCM and they serviced it.

Watch this video and do #7.
http://youtu.be/IqId0PMdPYA

[Uffdaphil]

Carrier and bolt are new and appear fine. No obstruction in carrier gas key. I'll be subbing a known good BCG to rule that out. The BCM lo-pro gas block (set screws) appears tight and in place. I believe the barrel is dimpled to locate block correctly.

Good video. Did #7 without a straw. No leak, discovered that Slip 2000 does not taste so great and lingers on the lips.

[GOST]

Not from own experience but I've read that LMT enhanced carriers helped with over gassed systems. BCM's gas ports are usually on the smaller side. Have you tried another carrier in this build yet?

[Eric]

You need to test the gas system for full function. Load a single round in the mag and fire. Repeat several times. Does it reliably lock open on the empty mag? If not, you're most likely loosing gas somewhere or have insufficient gas pressure.

[Uffdaphil]

Will have to wait for next week range trip for definitive testing.

[WHSmithIV]

While you're waiting, get some 0000 steel wool and polish out your chamber. Mine had an issue where the fired case was sticking some in the chamber with the brand new barrel.

[mustangfreek]

Try a different bcg , i recently had a problem at first with a 10.5" build, swapped bcg's and for some reason runs perfect now..

[Gaspipeshooter]

Try a different bcg , i recently had a problem at first with a 10.5" build, swapped bcg's and for some reason runs perfect now..

Good advice, which is why I was trying to clarify if the OP's problem was a failure to eject, or a failure to feed. Sounds like your original bolt had an issue capturing enough gas pressure to cycle the gun.