Recently I've been seeing quite a few brand new rifles coming in the shop with some sort of purple stuff on the bolt face, lugs, and in the bore. These have been Savages, Remingtons, and Winchesters. The stuff comes off reluctantly with Shooter's Choice, not at all with safety cleen solvent, and easily with acetone. Anybody else seen this and do you have any idea what it is, or why it's there?