AR-15 Trouble

Bartholomew Roberts · July 7, 2000, 12:01 PM

Have a friend with a Colt Heavy Barrel model. The gun only operates as a bolt-action. It will fire a shot but will not cycle. If the charging handle is used, it will extract the old round and load up another for firing.

Obviously the problem is somewhere in the gas system; but where?

I haven't been able to look at the weapon personally. I have recommended he check the key on the bolt carrier for any obstruction. He did and claims it is clean; but I am not sure he understood the directions 100%.

If the key is OK, then it seems that the gas tube is most likely blocked or bent and needs to be replaced. I haven't worked on Colts before and have some limited experience on mil-spec AR-15s from Oly, Bushmaster, PWA...

The Colt has a solid pin instead of a roll pin holding the gas tube in. I am told that removing the gas tube in general is a chore and especially so on the Colt. Is this something that can be done by anyone who knows their way around an AR or is this better to send back to Colt and hope that he gets it back before his hair turns gray?

Coinneach · July 7, 2000, 03:06 PM

Make sure the gas rings are staggered, like the piston rings in an engine.

Bartholomew Roberts · July 7, 2000, 03:35 PM

Thanks Coinneach, but he did check that one and reported that they were OK.

**4V50 Gary** · July 7, 2000, 11:37 PM

I'm curious as to how fouling is around the bolt carrier after he shoots. Does he use pipe cleaner to clean out the bolt key?

If it is relatively clean, then I would suspect something is wrong with the gas tube. Remove the handguard and examine it and the barrel for signs of leak. The gas tube may have to be replaced.

The worse case scenario is that Colt made the gun California compliant by not drilling out the gas port hole in the barrel - thus making it a manually operated straight pull bolt gun. I'd love to have that barrel if that's the case.

James K · July 9, 2000, 12:55 AM

It is not a big job to remove the front sight block and the gas tube. Then check the gas port in the barrel. (I have seen one replacement barrel where the manufacturer forgot to drill the hole!) If that is OK, check the tube. It is pretty hard to clog that tube (the early service problems notwithstanding), but it can happen.

Jim

**4V50 Gary** · July 9, 2000, 12:46 PM

Yep, roll pin punch is all you need to drive the pin out which retains the gas tube.

July 7, 2000, 12:01 PM	#1
Bartholomew Roberts member Join Date: June 13, 2000 Location: Texas and Oklahoma area Posts: 8,462	Have a friend with a Colt Heavy Barrel model. The gun only operates as a bolt-action. It will fire a shot but will not cycle. If the charging handle is used, it will extract the old round and load up another for firing. Obviously the problem is somewhere in the gas system; but where? I haven't been able to look at the weapon personally. I have recommended he check the key on the bolt carrier for any obstruction. He did and claims it is clean; but I am not sure he understood the directions 100%. If the key is OK, then it seems that the gas tube is most likely blocked or bent and needs to be replaced. I haven't worked on Colts before and have some limited experience on mil-spec AR-15s from Oly, Bushmaster, PWA... The Colt has a solid pin instead of a roll pin holding the gas tube in. I am told that removing the gas tube in general is a chore and especially so on the Colt. Is this something that can be done by anyone who knows their way around an AR or is this better to send back to Colt and hope that he gets it back before his hair turns gray?

July 7, 2000, 03:06 PM	#2
Coinneach Staff Alumnus Join Date: February 23, 1999 Location: Denver, CO Posts: 4,272	Make sure the gas rings are staggered, like the piston rings in an engine.

July 7, 2000, 03:35 PM	#3
Bartholomew Roberts member Join Date: June 13, 2000 Location: Texas and Oklahoma area Posts: 8,462	Thanks Coinneach, but he did check that one and reported that they were OK.

July 7, 2000, 11:37 PM	#4
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 22,306	I'm curious as to how fouling is around the bolt carrier after he shoots. Does he use pipe cleaner to clean out the bolt key? If it is relatively clean, then I would suspect something is wrong with the gas tube. Remove the handguard and examine it and the barrel for signs of leak. The gas tube may have to be replaced. The worse case scenario is that Colt made the gun California compliant by not drilling out the gas port hole in the barrel - thus making it a manually operated straight pull bolt gun. I'd love to have that barrel if that's the case.

July 9, 2000, 12:55 AM	#5
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	It is not a big job to remove the front sight block and the gas tube. Then check the gas port in the barrel. (I have seen one replacement barrel where the manufacturer forgot to drill the hole!) If that is OK, check the tube. It is pretty hard to clog that tube (the early service problems notwithstanding), but it can happen. Jim

July 9, 2000, 12:46 PM	#6
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 22,306	Yep, roll pin punch is all you need to drive the pin out which retains the gas tube.