[Shade]

I wanted to bounce a few questions off the members here. I purchased a
new Bushmaster Target AR about 2 years ago, between 3000-3500 round I
had a failure to cycle (FTC) problem. The weapon would fire and short cycle
leaving an empty chamber. Called Bushmaster and was told it was the gas
rings, that they only last ~3000 rounds between replacement. But on
removal and inspection that was the culprit, one had worn about 1/3 off and
the other were nearly there.

Replaced them and I was off to the races again. Well my round count is
getting close to that 3000 mark and it is time to look at replacing them
again. For one the bolt is "loose" in the carrier, by loose I mean it will not
hold up the weight of the carrier.

I did not replace them with the standard set of 3 rings but the helical wound
ring sold by Brownells. The Bushmaster tech did not recommend it but I
bought it an it has worked well so far. Generally, after I shoot I do a quick
clean and wipe and take a swipe or two down the barrel with oil and oil every
moving part with a drop or 2 of oil including the rings and a drop down the
gas key. About every 1000 rounds I tear her down good and clean
everything, since switching to Accurate 2230 for my reloading things are
much cleaner.

I searched and read and read and read and this is the only thread I could
find:

http://www.firearmstalk.com/forums/f20/gas-rings-gas-pistons-10709/

10,000 rounds on a single set of rings seems high given my experience but
maybe I am missing something here.

My questions are:

1) How many rounds do you fire between changing gas rings?

2) Is there a difference between different mfr's of gas rings or styles of gas
rings? What do you recommend?

TIA,
Lemke

[Quentin]

Replacing gas rings at 3,000 rounds isn't unreasonable wear and at least gas rings are cheap. It's definitely time if the carrier now slides down on the bolt during your test.

Is your carrier chrome lined? I'd expect that a nice slick carrier reduces wear better than high end gas rings. And maybe more oil in the BCG. Honestly I haven't tried anything but milspec rings you can get almost anywhere but a lot of guys swear by the McFarland one-piece gas ring.

[Shade]

In one of the older threads I read looking for information on gas rings.
One of the member here made comment that some old DI probably
told a bunch of recruit to make sure that the gas rings were 120
degrees apart and that they move around alot in shoot and their
alignment does not really matter.

The second part I agree with just as with reciprocating engines
compressors etc. everyone tells you to rotate the gaps but in
real life this is fairly pointless as the rings rotate freely and as
best as I can tell randomly in use.

However I did find it in writing...

Bushmaster owner's manual.

[robocop10mm]

Staggering gas rings is an old DI's tale. They stagger themselves when the bolt is worked a few times. 3000 rounds on a set of rings? That is an early failure as far as I'm concerned. I have never had to change a set of rings, EVER! I changed mine out to the McFarlands just because I found them on sale. I saved the OEM rings just in case. If your rings will not pass the hanging carrier test, they are indeed bad. Why they went bad is had to day.

Gas rings should be clean and DRY! Try Sentry Solutions powder lube on the rings.

[SecPro]

I just learneded me something here today. Damn good info here.

[Shade]

Originally Posted by robocop10mm

Staggering gas rings is an old DI's tale. They stagger themselves when the bolt is worked a few times. 3000 rounds on a set of rings? That is an early failure as far as I'm concerned. I have never had to change a set of rings, EVER! I changed mine out to the McFarlands just because I found them on sale. I saved the OEM rings just in case. If your rings will not pass the hanging carrier test, they are indeed bad. Why they went bad is had to day.

Gas rings should be clean and DRY! Try Sentry Solutions powder lube on the rings.

Got a few more pages of the Owner's manual to post that clearly state to
lubricate the gas rings and to put a drop down the bolt key. Next time I
shoot the AR (likely this weekend since my 8 year old was complaining that
he didn't get to shoot it this past trip to the range, my lovely wife said I
need to reload some ammo and let him shoot nest trip and soon before it get
too cold.... yes dear!) I will clean it completely and dry lube the rings and
install a new set of gas rings I have both the set of three and the helical one
peice unit.

[Quentin]

I've always oiled the gas rings when I clean the bolt, never gave it much thought...