Bob, there's only one thing wrong with what you're doing, as far as seeing if your BCG is in spec.
There is no defined set of plans, or design specs, on a 308AR.
Chances are, AIM is gonna come back to you and say, "It's perfect! We contacted the manufacturer, and what you gave us matches their design drawings exactly!"...
That is one of the hazards in building a 308AR. There is no Technical Data Package to follow, no set specs.