I have two of Dave Van Horn's barrels - a 10" .410 for Contender, and a 18" 30-06 for my new Encore. It is a heavy, slightly tapered barrel -very "stout" looking.
I just shot the 30-06 today for the first time- sighting in a scope. I didn't measure groups specifically, but the best looking group at 100 yds was under 2 inches (Factory ammo - Winchester 150 gr power points). I was shooting off a sandbag, and imagine that with a better rest (or better shooter!) it could be even tighter.
I have been to his shop, and he is a busy guy. He keeps a fulltime gunsmith working in addition to himself, and possibly there is third person machining barrels. He has an extensive list of calibers he will build - . I think his website is probably a little out of date - he mentioned that he was having some issues with that.
Dave seems to be a very exacting fellow, and has high standards, or at least strong opinions about "the right way to do things." As a small example. He won't use screws, like T/C does - he only uses allen head or Torx head bolts. I also noted that the forend bolts he supplied with his barrel were much heavier than the standard T/C forend bolts. So, little things like that say alot to me about his approach to making his products.
I'm not a target shooting expert - just a hunter, so I am not an expert on getting the last few fractions of an inch of accuracy out of a barrel. I bought his barrel because T/C doesn't make many carbine barrels, and that's what I like. I'd buy another barrel from him.