Bravery is a primary concern!!
Every now and then I'd come across an attaching screw on a pre-war target that very clearly was not the least bit inclined to move. Don't even think about it!!
Off I go to my gunsmith. About 10 minutes, and $20 later, back he comes, gun in hand---screw loose. If one were so gauche as to ask, "How'd you do that?!", he'd say, "It's amazing what a little heat will do." Now I knew better than to ask, "How much heat---and where?", because the answer to that is what the $20 was for. (And he NEVER boogered a screw, or put a scratch on the frame!!)
After not too long of pondering bravery, and one thing and another, it occurred to me the screw would be a whole lot more inclined to move, and move in short order, if you could get some magic screw thawing potion directly to the threads----and quickly! (Kroil works GREAT!!)
Here's how: Elevate the sight enough to expose the channel in the frame under the tang---and the higher you elevate the sight, the better----run it right on up. Secure the gun in an upright, barrel somewhat down position; and pour some magic potion directly into the channel---so it'll run right down directly to the threads. Then go do something worthwhile for a spell----like play with your children's mother.
When you come back, and give that screw another try, it's going to come loose----and all this is going to take a whole lot less time than pouring the magic potion on the screw head----time after time after time, and waiting for days for enough of it to seep past the head to get to the threads.
All this comes under the heading of time management-----and aggravation management--and $20 per screw management.
Ralph Tremaine