AR won't eject

[TripleDigitRide]

A friend's AR won't eject the spent casing. When I slowly pull the charging handle back, the spent casing seems to eject just fine. It's acting like the BCG is traveling too fast for it to properly eject. It seemed to function just fine during the last trip to the range. He took it home and cleaned it, and everything else should be the same.

[BrasilNuts]

Is the bolt even cycling when the round is fired?

If he cleaned it and clogged the gas tube, it would become a single shot rifle.

[whitewolf001]

:hijack:  This raises an excellent question, how does one clean a gas tube without removing it completely?

Edited December 20, 2014 by whitewolf001

[Oh Shoot]

P

 

...It's acting like the BCG is traveling  too fast for it to properly eject. It seemed to function just fine during the last trip to the range.

 

Severe overgassing can cause probs for sure, but If working fine last time but not this time, especially with same ammo, likely the opposite, too little gas, something changed.

 

Is it jamming, stovepiping, or just doesn't move back bolt enough to eject round and pick up another? Also, relatively definitive test -- load single round, fire, does it lock back bolt? Every time?

 

Pinned A2 gas block or smaller railed or low profile one? If the latter two, possibly it loosened up, maybe have even moved off barrel port. Also check gas key on block carrier for tightness. Who built it? Is gas tube pinned correctly in block?

 

Gas tube blockage is so rare it's not even on the flow chart for initial diagnoses, unless you shoot a lot of .22lr with adapter.

 

- OS

Edited December 20, 2014 by Oh Shoot

[KKing]

Is the extractor pulling the spent shell out of the chamber at all? Sounds like it may be skipping over the rim of the case. Which could be a weak extractor spring or over gassing. If it's a weak spring, I'd upgrade the spring, insert, and o ring to this...
http://www.bravocompanyusa.com/BCM-Extractor-Spring-Uprade-Kit-p/bcm%20extractor%20spring%20upgrade.htm

If it's just extremely over gassed, you could add a heavier spring and or buffer, but that's only a bandaid for decreasing the amount of gas. Edited December 20, 2014 by KKing

[Oh Shoot]

:hijack:  This raises an excellent question, how does one clean a gas tube without removing it completely?

 

Best way to keep it free flowing is not to mess with it at all. Only exception I know of to even expect a prob with it is if you shot a ton of .22lr with adapter and switched back to .223 and had failure.

 

- OS

[dcloudy777]

Simple, free stuff first:

 

Try different magazine.

 

Try different ammo.

 

Is the ejector moving freely and under spring tension?

 

What sort of configuration gun are we talking here?  (barrel length, gas system length)

[dcloudy777]

Best way to keep it free flowing is not to mess with it at all. Only exception I know of to even expect a prob with it is if you shot a ton of .22lr with adapter and switched back to .223 and had failure.

 

- OS

 

Yep.  I'm sure clogged gas tubes happen, but I've never seen one.

 

Continual shots of 50K+ PSI gas at very high temperature tends to keep plumbing pretty clean.   :pleased:

Edited December 20, 2014 by dcloudy777

[TripleDigitRide]

The gas block shifted just enough to cause the problem. Thanks for the info, fellas.

[dcloudy777]

The gas block shifted just enough to cause the problem. Thanks for the info, fellas.

 

That'll get you every time.  Fortunately it's a cheap easy fix.

Edited December 20, 2014 by dcloudy777

[whitewolf001]

The gas block shifted just enough to cause the problem. Thanks for the info, fellas.

Low Pro?

Edited December 20, 2014 by whitewolf001

[Oh Shoot]

Yep.  I'm sure clogged gas tubes happen, but I've never seen one.

 

Continual shots of 50K+ PSI gas at very high temperature tends to keep plumbing pretty clean.   :pleased:

 

Yep, the crud is self-limiting, in same way you don't need to use giant pipe cleaner on your car's tailpipe. ;)

 

- OS

[TripleDigitRide]

Low Pro?

Yep. I checked it when we first started having the issue, but it wasn't quite "off" enough to tell. After 60+ rounds of manual ejecting, it loosened enough to become obvious.

[GhostRecon21]

What brand gas block is he using?


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[TripleDigitRide]

What brand gas block is he using?


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I'm not sure. There aren't any markings.

[Lumber_Jack]

I'm not sure. There aren't any markings.

Does it attach with small set screws? He can simple the barrel to help keep it in place. Or get one that clamps on

[TripleDigitRide]

Does it attach with small set screws? He can simple the barrel to help keep it in place. Or get one that clamps on

His has the two set screws on the bottom. He is going to dimple the barrel.  

[superduty]

Same thing happened with mine. YHM set screw low pro gas block. I took it off and reinstalled it- no problems now.

[mikegideon]

Low Pro?

 

I always Loctite the set screws in gas blocks. Not sure that it helps. 

Edited December 28, 2014 by mikegideon

[whitewolf001]

I always Loctite the set screws in gas blocks. Not sure that it helps. 

Red Loctite or some other form of Loctite sorcery?

[mikegideon]

Red Loctite or some other form of Loctite sorcery?

 

I use blue. Then, make sure they're torqued down with a Fat Wrench. I don't use gas blocks that screw into the barrel. I always use clamp type. if you want something that won't come off with heat, you can always do this...

 

http://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/thread-locking-liquids/rocksett-prod54624.aspx

[Paletiger13]

Check to make sure the bolt assembly is properly staked