Help me diagnose my AR

[Smiley]

Hello all,
It seems that after a fun day at the range with my 16" Bushy the last few rds were starting to jam up. It seemed like the extractor was not throwing them away before the bolt could not only move a new round forward but also neatly place the spent catridge holding the bolt open. This happened about 3 or 4 times and I figured its time for a good cleaning. I probably had about 700-900 rds through it without cleaning and soem dirty ammo. But the last time it jammed it actually stuck the spent case between the upper part of the bolt and the upper receiver. It jammed it in there so good, we needed two guys and a screwdriver to unstuck the cartridge.
Afterwards, one of our shooting party commented that he thinks that the gas tube is bent since when the upper receiver is seperated from the lower and we just let the bolt slide forward into place it doesn't go all the way home. You need to push it that last 1/4 inch.
Now I have taken it home, ccleaned it down some and removed some debris that was in the recoil spring in the buttstock (Piece of rubber that came off of the buffer) and it seems to function fine with normal action. The bolt still needs to be pushed that last 1/4 inch when you are just letting gravity do its thing with just the bolt and upper.
The gas tub in the upper doesn't appear to be bent to my eyes.

Are there any indications that I should be looking for to see if the gas tube is bent? i probably won't have the time to go to the range until another week or so, and I would like to avoid the cost of a gunsmith since a gunshow is coming up soon.

Any opinions on my situation?

 

[RJ357]

Check that the gas key has not come loose on the carrier. That could cause both the difficult closing and the failure to eject, through gas pressure loss.


If that's OK, check the front edge of the key (the part that the gas tube enters into) on the bolt carrier. If the gas tube is hitting it, it will be marked up at that point. If you can see where it is hitting, then you need to carefully pry the gas tube slightly back towards the center of the channel. You determine which direction to move it by where it is hitting. You might have to place a spacer in the channel to pry against. Don't pry on very end of the gas tube, where the enlarged part is. It's a little tricky, takes some trial and error. It tends to just spring back, and it's hard to tell if you actually changed it. Start small, and gradually increase the prying force until you get a change in gas key clearance.

Also check that the barrel hasn't come loose. Try twisting the barrel (by the front sight) in the upper. It shouldn't move, of course. If the barrel nut has loosened, it could shift the gas tube to one side.

A misaligned gas tube would not likely cause that ejection problem, though. More likely a clogged or leaky gas system. Like leaky gas rings.

 

[Redlg155]

It is perfectly normal to have to give your AR bolt a slight push at the end when manually inserting the bolt. That doesn't have anything to do with the gas tube. What you feel are the locking lugs engaging and the cam turning.

If you are really wondering if your gas tube is making contact, then remove the bolt and place just the carrier back in the weapon to see if you are making gas tube contact. I'll bet you aren't.

Just give her a good cleaning and all should be well. When you put the extractor back in make sure you have the spring and the little blue rubber peice with it. You should also check the carrier key and make sure it isn't loose and the bolts are firmly staked.

If it's been 700-900 rounds then you wer due for a cleaning.

Good Shooting
Red

 

[Darkside]

You have gotten good advise above, but nobody has asked if you are riding the bolt(easing it forward) or letting it fly forward under spring power like you should. If you are riding the bolt, one thing to look at is the charging handle latch. Sometimes a little drop of lube where the catch hook slides over the receiver and into the locking notch is needed.(clear as mud...right?) One test I do is ease the charging handle down until the hook is just touching the receiver ramp and stop it there. Then with light presure just touch the charging handle release catch and see if the bolt engages the lugs under spring presure. If this is a new rifle it will take some time to "polish" this area. Just put a drop of CLP there to smooth it out.

Darkside