I use the same approach as Mr. Guy. 4d finish nails, #49 drill bit, you get a million zillion for a couple of bucks. They are softer than stainless and piano wire but I have never had one mushroom, I guess it could happen. I don't understand why you would need them that tight to begin with. I take it one step further, after I cut them to length, I fire blue them and rub a little bee's wax on em. I don't know if this is a good approach or not, but it has worked for me. I hunt in butt deap snow and considering everything, I've never had a problem removing a barrel. Sorry for the ramble