I acquired an A-5 magnum 12 that belonged to my wife's uncle's father in-law. He was a hunter and guns were simply tools and didn't get much special care. Barrel was clean but not much else. Metal is only fair and the screws only show a little ham-handedness. Wood's in decent shape. It has a 30" full choke barrel and he had mounted a red-dot sight on it and the mount was both screwed and epoxied to the receiver. I got it off but there is some staining from the epoxy and the screw hole plugs are unsightly but fitting solid plugs and matching the machining in a Belgian from 1959 would take a special kind of person. I am in the process of a deep clean. I got the special screw bits from Brownell's and was having pretty good luck till I got to the lifter/elevator screws. The locking screws came right out but the big lifter screws will. Not. Budge. So tight or stuck that I've bent the bits (but not added any marring to the screws). I've treated them with Kroil and tried but nothing. They're soaking now. Any suggestions?