I'm getting ready to do a "dissergy" style build. Last night I decided to see how well the barrel fit to the upper. The indexing pin stops about 1/16th of an inch from becoming fully seated in the upper. The notch is deep enough to allow a full seat, just, apparently not wide enough all of the way.
Is this something that will be taken care of as the barrel nut is tightened down? (my guess is yes) or should I relieve the notch a bit with a file first?
I'd have the rifle assembled, but I'm shipping the barrel for it (and one other) off to ADCO for some work.
My guess is that the barrel nut will take up the diffrence.
If not a little file will do it