When the USMC Armorer's were still building match M14's, I asked them what barrels they had on the line. Well, they had everything. Barrel makers would give them barrels, and as long as the barrel made a three inch ten shot group at 300 yards, it was good to go.
In my experience, all the match barrel makers produce good barrels. Sometimes I have heard about funnies, such as the newly chambered barrel that shot so far to one side, that it ate up all the windage in the shooters scope. The gunsmith who barreled that rifle then purchased another barrel and installed that for the customer. The humorous thing was, the barrel that shot way off, the gunsmith had marked it before removing it. And a walk in customer, upon hearing about the problem, got the gunsmith to install the barrel on his rifle, but rotated so that the barrel now shot low, very low. And it made an outstanding 1000 yard rifle. The shooter probably did not have to make more than a few clicks up to be in the center.
I have around three Kreiger barrels, they all shoot well, but they are all tight. Except a lot of load cutting till the primer popping goes away. Few of the shooters I know use Shilen, but the ones that do, are happy with their rifles.
The chambering job is just as important as the barrel. If the chamber is not perfectly straight and centered in the tube, than the barrel will not perform to its fullest potential. My gunsmith said he used a "floating reamer technique" at the very end of reaming, to counter issues with curvature of the drilled hole. The drill wanders when gun drilling, inbetween the ends, the hole can vary a surprising amount, and the gunsmith who reams the chamber needs to take that into account.
