My WOA 18" varmint upper with 1 in 7" twist on top of a Colt LE 6920 lower with a SSA-E trigger shoots less than 1/2" five shot groups at 100 yds. Give them a call they may have them in stock and ready to go. The 20" are only $285 with fitted gas manifold.
http://www.whiteoakarmament.com/xcart/product.php?productid=17824&cat=250&page=2