Have to add, a muzzel wear gauge checks this brand new barrel at "1". I "think" this is fair as the tolerance is .300 + .002. I do not know how accurate the gauges are, mine is a Fulton and new (used 4 times).

Does anyone know what the design parameters of the gauges? Anyone have a print? We all know a .300 pin will not enter a .300 hole, if a .2999 pin does it is tight depending on roundness and such. When I measure the gauge (bought 2 just to check them out-one to the other). They are about the same. I have to assume the gauges are screw machined off with the body large and the groves cut, then ground at a taper from end to end? One of mine is out of round by a few thenths or less. I am going to check it out using ring gauges just to check what it is doing. I do not have here at my house, have to visit a grind shop to have access to more accurate tools.

Like I said, I am new and just learning.