Based on my experience I can tell you that generally speaking, the good names will probably all be within a .002+/- . Colt has been pretty consistent across the board for several years as are BCM.

Quote Originally Posted by Jwknutson17 View Post
The problem here is that identical barrels with the same gas port can be completely different shooters. While it's a good place to start, based on the year the barrel was produced can lend complete different port sizes. It's kind of a crap shoot without production dates and when those runs took place.