Traudt from Green Mountain suggested their Reliability Product Improvement Kit. Are there more specific details?
The kit was tested at the Naval Surface Warfare Center in Crane, Ind., in 2001 and at Picatinny in 2002. It included replacing the extractor spring, ejector spring, gas tube and gas plug with more heat-resistant ones, and moving to a one-piece, four-coil system that was engineered from more thermally durable materials to make the gun function better.
Interesting, but it doesn’t seem to be anything revolutionary. I’ll bet the gas tube is made from incolnel (making it VERY expensive), and that the single-piece gas ring is McFarland COTS or a derivative of same.
The other springs are likely a CS alloy with some type of environmental coating. Lastly, the carrier and bolt seem to have some type of nickel-alloy coating (possibly NiB).