Guys, is there a rule-of-thumb about clearance between the bottom of a drilled scope mount hole and the top of a chamber or bore? This particular hole, should I drill it, would be for a 6-48 screw located directly above and maybe 1/4" in front of the chamber neck of a M44 M-N. There's about .340" between the top of the neck and the top of the receiver.
Edit: I just double checked my measurements, and there's .392" of metal thickness where I need a 6-48 hole. If I drill about a .192" deep hole will at least .200" be enough barrel metal in a high pressure area?
My 6-48 bottom tap has about a .060" tapered tip with no cutting threads. At .021" per screw turn, I need about .126" for 6 threads + about .060" for the tip = about .186" hole depth.