I have a savage 30 in 410 ga. that was kept in a moist basement for years and is quite rusty. I disassembled everything but the barrel. My question is how does the barrel attach to the action. It is so rusty that I can't tell if the barrel is threaded into the action or if it just slides into the action. I don't want to start twisting on the barrel without knowing what I'm trying to accomplish. I've been spraying it with penetrating oil for a couple of weeks and while I was able to remove everything inside the action the barrel just doesn't seem to budge. Any help would be appreciated!