Anti seize is what you want. You can get commercial brands made for muzzleloaders. You can go to an auto parts store and get some anti seize (but it is messy) or you can get some Slick 50 One Grease. I like to apply a layer of white teflon tape (plumbers tape) on the threads, then I paint some anti seize over the tape and also when you put the plug back in, finger tight only. Some even back the plug out about 1/4 turn. This will help it come back out after your day on the range. If you are going to be a time before you can get to the rifle after a range session, at least loosen or remove the breech plug from the rifle..