the way i check them is.... find TDC on each end, lazer between them from above the barrel.
adjustable beams are a must !!!!! i like a .003 beam cus i can just barely see it !!!!

place known straight base on until lazer crosses each hole inline.
punch, drill and tap......
been do'n it that way since they invented the laser level.
finding TDC is the critical part. do you know anyone that has optical alignment equipment ?
i think brownells and midway offer a guide to asist with this job. but i can't see a use for it cus my way works perfect.
i'm sure some of the guys here have a better way
your gunsmith probably will do you an excellent job
