Chamber reamers have a service life. One that is about used up will have a little less headspace than the first few barrels. Bolts do not get machined to the exact same specs all the time.
If you have a bolt for each barrel that closes on the go and doesn't close on the no go you are good.
These are hunting guns right? Not long range bench guns.
This might be what you are looking for.
Atom Optics 1 inch Scope Rings Mounts fit 11mm Dovetail Rails for Picatinny Rail Scope Rings High Profile One Piece https://a.co/d/hJV7LM5
A customer brought this in to the gun shop I used to work at. 300BO doesn't work in a 5.56. Mark those mags and pay attention. That was a Troy Industries upper.