Buy one of Constructor's barrels, a super bolt, and never look back. There are 1000s of post on the net proving the accuracy of his barrels and his service is top notch. He's a great guy to chat with about any questions you may have as well.
My current ARP 18" bbl is plenty capable of submoa. While it's given many 1/2" groups, it's not a 1/2 moa bbl by any means. It's dang sure plenty accurate for the ranges I'd use the cart for hunting. It also cleans very easily/fouls minimally. I like it enough that I'll be buying 2 more this year. May trip some of my Wylde bbls for his as well.
http://ar15performance.com/home 
