When I took the Long Range Firing School at Perry a few years ago, I used a single-shot .300 Win Mag bolt rifle, but was amazed with the number of participants shooting .223 AR's.  
Researching the available literature at that time, Feamster (in his Black Magic book) suggested a growing interest in 7- and 7.7-twist barrels with 75-80 gr VLD's for 1000 yard competition but the "jury was still out".  
What is the current thinking toward barrel twists for long-range (1,000 yd) shooting on a conventionally-configured AR-15, and what bullet weights work best with those twists?
Links to reference articles and current books on the topic would also be appreciated.
Since the best pricing is still at Camp Perry's commercial row during High Power phase going on right NOW(Bushy, DPMS, and RRA, as well as others are all there) and I live relatively close to it, I'd like to drive down for the day with one of my match uppers (fitted with an 8-twist barrel) and swap out barrel assemblies.
Any recommendations will be humbly appreciated.
Hank

"All skill is in vain when an Angel pees in the touch hole of your musket."

Krieger 1/7.7 is top quality these days.
Lilja, Douglas, Shilen, and Lothar Wather are also up there.

Krieger 1/7.75 for 80 JLKs