I guess the need/desire to lap depends on how you are using the rifle.
I shoot for accuracy, or try to. I have a rather heavy barrel, and shoot NEAR max with a 22Nosler.
Sometimes with a 5.56 bolt, and sometimes with a 6.8 bolt (Hagar brass necked down).
I desire the best alignment and stability I can get. Centering the barrel in the receiver bore and a flat and square 360 contact with the extension flange should help. My 1:7, 5R, 28" barrel doesn't seem to like 55gr bullets. The wind drift of the 80ELD @ 3000 or 88 ELD @ 2900 seems to be less than the lighter bullets.
Those that run modified bolts with a larger face and less lug support and hot loads should pay close attention to lug loading.
Once I shoot this barrel out I don't want to press the barrel out. So I won't be pressing it in.
A slight thermal fit can be tapped out with a rubber mallet.
If you are worried about headspace send a bolt to your barrel maker or buy one of theirs and specify what headspace you want.
They will run the extension onto the barrel to give you what you want. This is done before the port hole is timed (unless you ask for NO PORT
).
Work with your barrel maker.
Buy downstream from a bargain reseller or buy a cheap assembled upper and you may get a pig in a poke.
If you end up with a receiver face that you can SEE a gap at the extension flange, or slide a business card into the gap contact your receiver source.
For lapping we are talking about taking maybe one half to two thousandths off high spots to get full circle contact.
If you end up with feed ramp edges, blend them. Happens sometimes even without lapping.
