H&K and Sig 9mm (including MPX) use a M13.5x1LH (left hand) and a 12.5mm drill bit.338 Laupa Some use the .308 standard 5/8x24 tap and a 9/16 (.5625) inch drill bit while others like the Ruger Precision Rifle use a 3/4x24 tap and a 11/16" drill bit....