If the thread is a standard one perhaps you can make your own replacement? Brownells sells blank screws that can be used to create almost any screw. I sure know how you feel!! I hate some jobs.. Had a friend with a '73 winchester (22 short) and the dust cover screw had 1/2 the head snapped off. He asked that I remove it so I drilled it out but the stress was rough.. A good drill press vise and a center drill, very sharp, got it started off well centered. All came out well in the end, no marks and the replacement left no evidence of any problem...