80% lower finishing

[RandallZ]

At a minimum, you'll need a 5/6x4" center cut end mill, plus the drill bits for the trigger and selector pins. Using a 3/8 end mill will make a more conventional firing group pocket, but a 5/16 will work, too.

I would recommend working out some way to hold your drill exactly perpendicular to the jig. The mill and drill bits will eat into the jig as easily as the lower. Even a cheap import mill-drill from CraigsList would be better than trying free-hand.

Good luck with your project.

Randall