Drilled and tapped the receiver for the Weaver #1 base this afternoon. I use a Forster jig; have had it for years, have used it for many jobs.
This base requires four holes located on the left hand side of the receiver, along the waterline. The two front holes were straightforward. The rear two were a bit more challenging - the overarm jig which carries the bushings for the drill and tap could not clear the trigger housing, which is a semipermanent installation on the receiver. So, I installed the base using the front holes, and carefully centerpunched the positions of the two rear holes, using the holes in the base as guides. Worked well. All 4 holes drilled and tapped, properly located. No holes are out of line or crooked, and no taps were broken. All that remains now is to relieve the stock slightly to clear the bottom of the base.
I've never enjoyed drilling and tapping receivers or barrels. One of those jobs where the setup needs to be checked and rechecked before turning on the drill press.