The Shilen barrels Brownells sells are nice, very good quality barrels. The barrels Numrich sells are OK, pretty much like the Adams & Bennett barrels (better than factory, not as good as a Douglas) but at a higher price. If you like your A&B barrel, you might try a blank and have it threaded/chambered, it will cost about the same in the long run.
http://www.midwayusa.com/viewProduct...tNumber=426755