I'm a longtime smallbore shooter who decided to get into 3 Gun a while back so I built myself a rifle. Bought the receivers and BCG from a local place in Reno (US Firearms Academy- they're spendy, but they make some really good stuff with some really tight tolerances, and it' local) and got a Wilson Combat 3G trigger and muzzle brake and a Lilja M4 contour 17" barrel. Topped it off with a Burris Fullfield Tac-30- which I think is a great optic, super clear glass and the reticle is great for both close target engagement and shooting steel out to 500 yds.
Anyways, was doing some load testing yesterday off the sandbag and found I could not shoot anything bigger than a half inch group at 100 yards with 20 grains of 4198 behind 69 grain MatchKings. If you're in the process of a build, and want a super accurate (and super expensive) carbine-length barrel that's sub-MOA, look no further. I literally cannot say enough good things about this barrel.
Sidenote, if you get the Wilson Combat 3G trigger, it has a super short reset, and they warn you about bump firing. If you shoot off a bag, or slung up (which I do occasionally) you may find yourself occasionally ripping off a three or four round burst if you don't pay attention- but for rolling double taps on the move, it's great.
Was hoping to include pictures of the rifle tonight, but my camera decided to run out of juice and I can't find the charger.
http://i1259.photobucket.com/albums/ii543/ives5113/image.jpeg