New ones are supposed to be MOA right out of the box. They used to sell a sub MOA version. If they achieve their goal, I imagine all the older stock will go on one hell of a sale.
If you insist on 223 then make sure you get 1-7 twist to stabilize the heavier rds and you will be able to reach out to 600 yds. 1-8 or 1-9 and you can shoot all the NATO surplus fodder. The Mark Vs you can build from scratch, not sure about the Vanguard line. Short stiff med. contour barrels seem to be in vogue.