[TARNATION !!!]

David: For all screws, use hollow ground driver tips that fit the entire slot side to side and edge to edge and full depth. That is very important in order to not end up with messed up screw heads. Clean the slot fully of any crud/rust/debris first. Apply minimal torque. If the screw does not turn, use a drop or two of penetratiing oil. Let it work for a while then try minimal torque again. Eventually, you win and have intact screw. Lose your patience and you lose the screw head. In the case of the trigger guard screw head, you are dealing with a wood screw so it should come out readily enough. The trigger guard screw that threads into the floor plate may need a bit of penetrating oil or may turn fairly easily. Good luck
Jack