Most of us usually install the base pin, screw down the set screw to mark things, remove & LIGHTLY indent the spot with a drill bit.
Or, you can also use a pointed punch pin, (machinist type) to mark the spot. You install the base pin, take the set screw out, slid the correct sized punch pin in the slot, tap it to mark the bbl. Then remove it all, and again, align the bbl in a press & lightly indent to bbl with a rounded depression for the set screw.
You don't need a " hole" for the set screw.