If your bolt is becoming stiff then I'm assuming that it was ok at one time. Most likely not because of a burr. I would try taking the bolt out of the receiver then spraying in good with carb cleaner, let it set a while then spray it again heavily to wash out any gunk. Dry it off good and let it set to dry. Afterwards use some good oil sparingly getting it into the rotating areas of the bolt. I like the rem oil in the little bottle, it seems to flow into tight places. It may or may not help, but that's what I would do.