I've been Chief Designer at Continental Machine and Tool Co. off and on since 1998 (with some time off spent at Smith and Wesson). For reference, we make our own retail product, Stag Arms, pretty much everything on the Colt's Military M-16/M-4 except the barrel and plastic, and about all the parts in Rock River, Bushmaster/Remington, and a lot of Armalite. I worked at Colt's on the M-4 design team back in the early '90's, and I've worked with Roy Piontek down at E.R. Shaw for about 12 years.
Roy, the former general manager of Shaw, took the place over about 11 years ago, and turned the product from O.K. to amazing. Let me stress this one point: I've seen hundreds of thousands of his barrels in the last dozen years, and they are the best mass produced barrel in the country, sold for $20 less than their competitors.
They make Remington's centerfire barrels. Anybody who can cut a 40X can make my AR-15 tube any day. On average, a Krieger, Obermyer, Pac-Nor, or Lilja hand cut barrel will edge out most Shaw barrels by a small fraction of an inch at a hundred, at three times the price. But even there, I see so many amazing exceptions.
Unless you're an olympic competitor or a military sniper, is it worth the extra 200 bucks to shoot three eighths of an inch instead of three quarters?
A Douglas Premium (only 15% of their production) will about equal the typical Shaw, and a Hart will often shoot with a hand cut Krieger. But remember, what gets sold as a Hart is, like the Douglas Premium, a small, select portion of their production, most of which gets sold under other names.
My meat guns (.358 Norma Mag and 30-06) are built around barreled blanks I got from Shaw, and I compete in Highpower with a bone stock 20 inch AR heavy profile. 24.5 grains of 4895 and a 77 grain MatchKing benches me close to half MOA with iron sights, all the time. That's 50 shots across the National Match course and 10 foulers and sighters, a match and a practice session minimum each month.
Again, my opinions are based on close to half a million barrels, over more than a decade. Consistency of the rifling twist is flawless. Most manufacturers stretch the front few inches as the button runs dry. Roy doesn't, and no, I won't tell you how. Bore and groove run within two ten thousanths at worst, and if there's a taper, it's only a tenth or so, and gets smaller toward the muzzle for gas control.
The critical function characteristic of any M-16/AR-15 barrel is chamber finish, and if it's over 12 or 14 micro, reliability goes to hell. Shaw's stuff runs a 6 at worst, and I've seen 2's.
Simple comment: If my butt was on the line and I had a factory made weapon in my hands, I would want the barrel to be a Shaw.