If you want the BEST barrel you need to talk to Jim McLemore. I have a McLemore barrel that has won about 200 bucks in the 3 matches its been used in. If he does not make the best ML barrel I would like to know who does better. His use of 4150 GB quality is important to me as well and should be to everyone. He also uses relatively shallow grooves which is a plus. That shallow groove work has been known for about 200 years at least. With 4150 wear is not a consideration.
http://www.sleepyhillbarrels.com/Products.htmlThe internal finish on Jim's barrels is superb and the uniformity of the dimension is excellent. Between me and two friends we have 7 of these in 45 and 50 caliber and they are ALL very superior barrels. Though my 50 is the only one built into a rifle to date. It shoots so well that I only shoot it now and then in matches. These really are premium barrels.
Green Mountain barrels are excellent, priced toward the lower end of the spectrum and are made by a company that makes barrels for brass suppository guns as well so they make a LOT of barrels. To the point that ML barrels are a side line, they are made of a high quality steel of a reliable alloy, 1137 and shoot extremely well. The also load easily with a tight fit or hardened lead. Some of the early barrels had problems with EXTERIOR finish but the interiors are always good. Grooves are not too deep so they seal well.
Tip Curtis usually has a good supply of GM barrels. I think they were tied up with Gov't work for a time and this would prevent them from making 1137 barrels. I don't know if this is still the case.
TOW has GM as well but the supply has been sporadic.
When I can get barrels from Jim or GM I don't need any others.
I have seen a GM 45 caliber barrel shoot a sub 3.5 inch 10 shot string at 60 yards. This is an average deviation of less then .35" from center. Load easy, shoot great GB grade steel.
There are others that use better quality steel as well, I think Long Hammock is one.
Dan