LMT is first quality - definitely reliable. Availability on the commercial side has been an issue. They are not as common because the focus on .mil contracts, both for guns and replacement parts for other manufacturers weapons and also do (or did) OEM manufacturing for other brands.
Their AR-10 is the standard issue DMR for UK and other commonwealth forces including the New Zealanders who have now also replaced their AUGs with the LMT MARS 5.56. The MARS is the latest version of LMT's monolithic rail piston gun.
I have two of their DI guns purchased back in 2007 when Colt 6920' s were unobtanium due to war production. In the current market, LMT DI guns are a little pricey for what you get compared to say BCM, but the quality is there.
Karl Lewis sr and Reed Knight Sr go way back and there is some sort of professional relationship between the companies.