I have a pair of 1971 era Pedersoli pistols with screws that I can't remove. Which means I can't disassemble the guns for cleaning so I can't shoot them. Hopefully you guys can help me. These screws have the narrowest slots I have ever seen. You can only just fit a razor blade into the slots. All of the screws are the same and they also have a checker pattern top. I've tried a Brownells master screw driver set and nothing fits. Any ideas?