What is protrusion supposed to be?
WITHOUT the nut I can get the gauge to mate with the new Bolt head.
Seems it is the old nut...
I have an axis barrel I could use the nut from, however the nut will not come off... I think it's the blueing salts. Barrel is off the receiver, but that nut will only come off about 3 full turns and seizes up something fierce. Bluing salts everywhere...