Home Forums Hunting & Shooting AR and Tactical Rifles Gas key fitment

Took one of my lower tier ar's to the range for the first time that I had bought 10 or more years ago. After a few shots it quit cycling and had to mortar the thing to free up the bcg. Long story short I found that the gas key was still tight but misaligned on the bcg. After loosening the key I noticed that it had play in between the two rails on the bcg that it sits in allowing it to be tightened crooked. Is this "play" normal? I would assume the tolerance would be no more than .001"- .002"
All back together now with Loctite retaining compound and working fine.

I've never had one disassembled. Who is the manufacturer?

I swapped around a lot of parts so it is either a Delton or AR Stoner bcg

They need to be fitted to the carrier so they seal off good but I’ve never seen one with side to side movement.

What I see a lot of is the barrel nut not centered and the gas tube sitting crooked.

Yeah first time I ever had a gas key off and I was not expecting any clearance either. Didnt measure but I would guess .010" By changing bolts and then carriers I narrowed it down to the gas key on specific carrier. Once I found the culprit I could see it pushing the gas tube off to the side as they interfaced.

We had a series of carrier keys with soft bolts in the early M-16s, issued to the 101st Abn Div. The bolts sheared and blew the carrier heys off the carrier, making a fine single shot. The bolts are supposed to be staked with a center punch so they do not come out once torqued to spec and should all be hardened bolts. If I recall correctly, been a few decades, two #7s at about 80#s torque. The Key's mouth is fitted to match the gas tube and the base of the key is fitted to the top of the carrier with double sided emery paper, fit is flush and air tight, without any gasket or Locktite. Heat does release Locktight and the carrier key does get hot.

Thanks Rapier, while I had it off I flattened key and carrier with a stone, used LT 680 before torque and staking. Slides right on gas tube now, taking to the range Sunday with others to test.