I believe the Barnes coating on the XLC's is a proprietary coating of some type, and is not the "standard" moly coating that some use. The moly coating does indeed leave a wash in the bore, which builds up and may eventually be detrimental to accuracy. This crud is also kinda difficult to remove, as I understand it. I once used a moly-type "paint-on" cast bullet lube on some bullets i shot in a Ruger No. 3 .30/40 Krag. This stuff totally prevented leading, but accuracy deteriorated, and it was hell getting it out. It even made accuracy poor with jacketed bullets! I did eventually succeed in getting the accuracy back in that gun, but it took a while,a lot of Shooter's Choice, patches, and elbow grease.

The Barnes blue coating is supposed to provide all the "benefits" of a moly-type coating with none of the drawbacks. I believe this coating was originated to reduce the excessive copper fouling that some complained of regarding the original "X" bullets. The TSX apparently does not foul to a great degree due to the big reduction in bearing surface vs the old "X" designs, so the coating is not needed.