That's not to say all 'smiths' are equal. Quite a few AR companies cannot properly assemble ARs.
Actually the front of the threaded portion of an upper can be trued so that the barrel sits square in the upper receiver. A 'smith' should be able to properly assemble with the correct torque values etc. and should properly stake a carrier key, CAR/M4 stock nut. A 'smith' should check headspace, firing pin protrusion, and could ream the chamber to 5.56mm NATO and verify everything works properly according to the TM. Again not all 'smiths' are equal. Some 'learn' on your stuff.
I work on AR platform rifles and carbines daily both new and stuff people bring in. Most of the time I have to restake carrier keys etc (even on new stuff).
Chief Armorer for Elite Shooting Sports in Manassas VA
Chief Armorer for Corp Arms (FFL 07-08/SOT 02)
Bookmarks