Screw size for scope mounts on 24V Series D

if you're going to re-tap it really doesn't matter what the factory thread was.I usually select a common diameter sizeand matching thread and then its just a matter of selecting the proper drill bit and tap from a cheaper source than brownels.But you need to make sure you use a "bottom"tap because the re-drilled hole is not very deep and you want the threads to go all the way to the bottom of the hole.sometmes if i know i wont have a lot of depth to work with I'll break the drill bit off above the bevel so I only drill a "flat" bottom hole. A # 8 machine screw in a common thread turn is a very good holding choice along with loctite of course!On 2nd thought if you're not accustomed to machine work a tapered tap will be easier to start the tapping process with and then finish with the bottom tap.