I agree with Dennis.
When you order a select match grade barrel from a maker such as Shilen, Krieger, Hart or one of the others, you will get a barrel that is made to the same tolerances as the rest of the guys.
Some guys buy several barrels ( 4 or 5) at a time and test them all looking for the best of the bunch to shoot at the big match's.
I don't know if it means much but I like to check out the equipment list for the big matches and see what barrels are winning.
At last years Super Shoot their were 5 different barrel manufacturers in the top 20 of the 10.5 lb class.
Ted