In engineering terms a countersink is specified as the depth and the angle. In this case it would be 0.010 x 60 degrees(countersink bits come in 45 and 60 degrees). Ideally this should be done in a vertical mill. There is a video on the Internet somewhere on how to replace oring on Daystate mags.which can be used to disassemble although there is no oring on the .25.
Upvote 0
