AR Issues

[Gun]

I didn't see this mentioned. Check the gas rings. If they have the openings all aligned it creates a gas leak in the system and will short stroke the gun.

Threads discussing this @ m4c disprove this notion.

[wheeling365]

Threads discussing this @ m4c disprove this notion.

I'm going to have to respectfully disagree. I am a fulltime armorer for the gov. I've run across it more than I care to admit.

[Lycanthrope]

The gas rings can be in any alignment and she should run if everything else is indexed right. This would only matter if the rest of the system is marginal to start with.

You can put your fist over the muzzle and blow to see how much flow you have through the gas tube, but without experience you probably won't be able to tell if you have a misalignment. You can still have some airflow and shortstroke.

I'd rule out the lower and then start on the upper. If the ports are misaligned it's easy to fix. I use calipers to measure the edge of the gas block to the center of the hole. Then I measure a point on the barrel (usually the step in profile) to the center of the barrel port. Subtract the smaller from the larger and that's your feeler gauge distance from the step in the barrel to the edge of the block. Perfect center to center alignment.

Lycannoguessesthrope

[cpio]

I was just about to ask if the gas tube is properly indexed.

[Gun]

I'm going to have to respectfully disagree. I am a fulltime armorer for the gov. I've run across it more than I care to admit.

Discussion on alignment;

http://www.m4carbine.net/showthread.php?t=59254

... on gas ring problems;

http://www.m4carbine.net/showthread.php?t=126052

Quick test as stated in last thread, stand BCG on the bolt, with bolt extended. Carrier should not collapse downward onto bolt.

Rings are cheap, can fail prematurely due to inferior materials, or carrier is out of spec if rings look in good repair.

[17CulpeperMM76]

OK, there is definitely leakage around the tube at the gas block. Lots of discoloration (gray soot) on the tube...

I'm going to try and dig into this weekend and see what the issue is.

[Lycanthrope]

Gray soot on the tube isn't always bad. There is some natural blowby there if the tube doesn't fit tightly into the block.


Gray soot around the block base at the barrel can be a real issue.

What type of gas block is on this gun? Pics would help, too.

Lycanwouldpulltheblockoffandlookthrope

[17CulpeperMM76]

Removing the block is a weekend thing, so....

It is a flat-top block. Not a low-profile.

[Lycanthrope]

Pinned on, clamp on or set screwed?


Lycan30minjobthrope

[17CulpeperMM76]

I guess you would say it is clamped on. Two Allen head screws do the clamping.