Warning

 

Close
Confirm Action

Are you sure you wish to do this?

Cancel Confirm
AR15.COM
AR Sponsor
3/24/2025 3:36:36 PM EDT
I have 2 14.5 lmt uppers. the one will punch an H2 geissele combo back and feels great. the other doesnt like the H2. went down to H1 and carbine buffer and it does cycle but every few rounds itll kinda spit one out. about 3:00 with an H1 and every few or so there will be a weak/sloppy eject. tried a new bcg with it as well. almost like theres a leak but cant locate it. Gas block doesnt seem loose. key and tube match up nice and smooth. Any idea what might cause this? It aint that dirty. Any way an lmt G block is not alligned right or becoming loose? going to try to scrub it and air spray tube
3/24/2025 4:22:48 PM EDT
[#1]
barrel port hole blocked or under size?
3/24/2025 4:54:06 PM EDT
[#2]
no idea. its an lmt barrel. havnt taken one apart. could maybe send it in for a check if cleaning doesnt fix it. its cycles, just struggling here and there. i can feel it too
3/24/2025 5:20:41 PM EDT
[Last Edit: bfoosh06][Edited] [#3]
Does the "weak" one lock back on a single rd loaded /fired from a mag, 100 % ?  Even with weak ammo ? ( PMC Bronze )

Any visual signs of gas leakage ?

Ejector functioning well ?

What do the fired cases look like ? No scratches , etc from a rough chamber ?

You might try swapping the bolt, between the 2.

Factory ammo ? ( not reloads ) maybe one has a tighter chamber.

Just thinkin' out load.
*Hold on to your AR-15s. Their magic must be very powerful, or they wouldn’t want them.*
JAFOM.... Just another fat old man.

________________________________

TOGC,IADC
3/24/2025 5:53:53 PM EDT
[#4]
i will try that out on the lockback this weekend. it was happening with the same ammo types and I tried different bolts. Ill check out the ammo after but I am not seeing excessive wear on feed ramps. feed ramps look good. I will check all that out. tried to clean chamber out. not sure if Im seeing any leakage. gas block looks solid. I will check those 2 things this weekend.
3/24/2025 8:52:29 PM EDT
[#5]
lock the bolt back, plug the breach with a spent shell, put finger on gas tube to block it and blow in the end of barrel to check for leaks.
take finger off of gas tube and compare air flow to the one that works to check for blockage.
3/25/2025 9:04:50 AM EDT
[#6]
Try swapping the bolt carriers, for a quick test, if you haven't done so already.

Just to confirm the problem is in the barrel.  I've seen intermittent issues when a gas carrier key screw fails.
WTB: Steel Bodied Surefire Trainer
3/25/2025 11:43:07 AM EDT
[#7]
Quote History
Originally Posted By Postal0311:
Try swapping the bolt carriers, for a quick test, if you haven't done so already.

Just to confirm the problem is in the barrel.  I've seen intermittent issues when a gas carrier key screw fails.
View Quote

"tried a new bcg with it as well."
3/25/2025 2:41:03 PM EDT
[#8]
out of curiosity ,  how would a rough chamber cause undergassing? havnt heard of that
3/25/2025 5:25:45 PM EDT
[#9]
i tried that too. it pushed the casing right out. no feel or audio on any leakage…wierd. going to try to clean chamber out and throat as well as i can. maybe some nasty shit got in there. also going out this weekend and im going to try a different barrel in it too

Sign up to continue the discussion

Create a free account to share your thoughts, follow topics, and connect with the AR15.COM community.

Already a member? Sign In

AR Sponsor