Easy Gas Rings And Carrier Key Alignment/Wear Checks ...
Gas rings may last 20,000 rounds. The longer they go, the better they have lapped in. Kinda like piston rings. A well broken in AR15 rifle carrier group/gas ring "friction feel" may feel slick and easy, but the rings are just doing their job correctly. No need to change rings just because gravity drops the carrier down with the group inverted on the bolt head.
I believe the "Colt" test was designed to sell gas rings? With high mileage rifles, if the rings are that far gone, then the carrier channel is also past spec and both will have to be changed out. This kinda dove ties with exterior carrier/upper receiver wear. The service life tends to be the same. But ... with broken/missing rings, change them.
The fun easy carrier key alignment test is fun and easy. Unload rifle. Separate. Strip out the bolt group. Invert the rifle muzzle down and drop the carrier with key down over the gas tube. The carrier and key should plop, (good word) down without touching the gas tube one little bit. No friction what so every. This can be tricky doing builds with loose parts.
Without seeing and handling the Rifle, it is difficult to state a problem or cause. There may not be any. Tolerances vary. Certain combinations of parts will result in different "feels" Actually, a "tight feeling" carrier group may be better. More room for precision and longer wear. Colt builds great stuff that may be tight. Hope this helps some.
HB of CJ (old coot) hundreds of AR15 builds and uncounted assisted with others thousands of M16 rebuilds. Long ago and far away. Now I want a left handed AR10 God help me. This stuff is so fun. Lefty AR10 uppers and carrier groups in the works, so my spies tell me. It would be so much fun to re enter the fun and madness.
