I think I'm going w/ the Gre-Tan drop in shroud, pin, spring. That spring needs to get replaced. I got out the rifle last night and noticed that you can hear and feel the spring moving against the bolt body when you cock the rifle.
The shroud to bolt body contact looks minimal, but I'm going to polish the bolt body behind the handle, where it contacts the shroud, to eliminate the matte finish.
I like the matte finish on exterior surfaces, but it is not smooth enough for slick metal-to-metal contact. It would cost too much for Remington to do that (polishing areas on parts) in the factory, so after-market or DIY, is the way to go. Lithium grease definitely helps, but smooth finished metal will be better.
