Aren't they already drilled and tapped? Mine is.
I am NOT, a Ruger xpert, yet, anyway, but my MkI, bought in 1977, is NOT drilled and tapped.
My 22/45, bought a few years ago, is .....
so it MIGHT depend on what year it was made .....
MK3 is drilled, MK2 im not sure about, MK 1 is not drilled.
If it were me I would buy one thats already drilled and tapped
MK 2 are not drilled.