308 AR bolt ring / gas ring per MIL-S-5059, U.S. Manufacture, pack of 3 or 9 rings.
There was a time when we thought about making improved gas rings.
The original design uses 3 thin split rings, ours would be somewhat
different. After considerable research, we moved on to something we
could actually improve on, for the 3 split ring design is still the best in
offering fault tolerance and redundancy.
is one of our LMT enhanced bolts. One of the 3 rings is completely
missing, the second one is severely diminished, and a piece fell out
upon our attempt to remove it, the third one is barely the same shape it
used to be. This particular bolt has been in use since 2005, it went
through mag dumps at the AZ Big Sandy MG shoots, as well as slow, aimed
fire, with various brands of ammo. When dropped into the carrier, it
offered almost no resistance. And yet, it was still working.
It is a testament to the brilliance of Eugene Stoner's design.
A simple test of dropping the bolt into the carrier can tell whether the
rings should be replaced, the bolt should not drop into the carrier
without resistance. While we're at it, we'd be remiss if we didn't
mention the futility of aligning the gas rings, it's an old wives tale
and has no merits whatsoever. The tapered bore of the carrier closes
the split rings as the bolt travels rearward, aligning them is useless