AR Question

[gkdir]

First of all "I,m not an AR person." I own one--I shoot it--I clean it--I put it away till next time. There's a kid down the road that has a Grizzly LAR,16" flat top. He calls me last night, says his AR is screwed up. WON'T EJECT! Do it manually and everything is fine. So to you AR guys---whats the problem? Thanks in advance,,would really like to help this kid--think he's gonna be one of the "good ones". I put this question down in the "Repair" section also to catch a different group.
G

 

[HOOfan_1]

Is the bolt going back but not ejecting the shells, or is the bolt not going back at all?

If the bolt isn't going back then he has some sort of problem with his gas system.
A leak in the gas tube. The gas block isn't lined up properly or something wrong with the gas key.

If the bolt is going back, but the cartridge is not being ejected, is the cartridge stuck in the chamber, or stuck on the bolt?

If stuck in the chamber...something is wrong with the extractor. Replace the spring and or the extractor.

If it is stuck on the bolt then something is wrong with the ejector...take out the ejector and clean the channel and or replace the ejector spring.

edit: it might also be something as simple as he isn't lubing it enough

 

[gkdir]

"If the bolt isn't going back then he has some sort of problem with his gas system.
A leak in the gas tube. The gas block isn't lined up properly or something wrong with the gas key."

This is basically what he described, so I have a feeling he's probably messed something up while attempting to clean. I'll go down later today and see if my limited capabilities can help him. Thanks
G

 

[HOOfan_1]

Here's a trick I used to make sure my gas block was aligned on the rifle I built.

My Daniel Defense barrel came with rubber caps to protect the muzzle and champber. I put on the muzzle's rubber cap. Put a dumby round in the chamber and angled it up to help gravity keep it in. Then I took some compressed air and shot it in the gas tube where if would normally mate with the gas key. If the dumby round shot out of the chamber, I knew I at least had some air flowing in the right direction.

Just be careful of your muzzle, and somone might say my idea was a bad one for some reason or another. A lot of people seem reluctant to let anything get stuck into the gas tube.

 

[Ramone]

front to back:

Check alignment of gas block or front sight

Check that gas tube is pinned in gas block

Check that the aft end of the gas tube is engaging the gas key.

Check for Crimp in gas tube

Check Gas Key- loose? Missing?

Aft that, you are looking for blockage in the gas tube or key.

 

[TonyAngel]

Geez guys. The rifle quit ejecting when fired, but does eject when operated manually. I agree that it's a gas problem, but jumping to the tube or gas block is kind of jumping the gun.

I'd look to the gas rings first. They are the parts most likely to wear out and are supposed to be changed every few thousand rounds assuming high quality rings. I've seen cheap rings go in as few as 300 rounds.

 

[HOOfan_1]

Geez guys. The rifle quit ejecting when fired, but does eject when operated manually. I agree that it's a gas problem, but jumping to the tube or gas block is kind of jumping the gun.

I'd look to the gas rings first. They are the parts most likely to wear out and are supposed to be changed every few thousand rounds assuming high quality rings. I've seen cheap rings go in as few as 300 rounds.

Yeah could be that too

I've read the best way to test for that is to pull the bolt fully forward in the carrier, then set the entire bolt carrier assembly up vertical resting on the face of the bolt. If the gas rings are good, it should support the weight, otherwise the weight of the carrier will push the bolt back into the carrier.

Conversely you can push the bolt all the way into the carrier and hold onto the bolt and see if gravity pulls the carrier down. The Army manual actually says to push the bolt into the carrier and then hold the carrier assembly with the bolt down, and if the weight of the bolt does not pull it down you are fine.

 

[rcmodel]

I'd check and make sure there are still three gas rings on the bolt.

Make sure the two gas key bolts are tight on the bolt carrier.

Also a good chamber cleaning with a bronze chamber brush & solvent.

Also take the bolt apart & clean the extractor & ejector.

Also check and see if the gas block shows any signs of turning off-center on the barrel. (front sight canted to one side) That can block the gas port in the barrel.

rc