I just got back from the range session with my Hart barreled Howa two-twenty-three. I'd loaded three different bullets: A Hornady 52 grain Match, a Sierra 53 grain Match, and a Speer 50 grain TNT. All flat based HP's.
I fired three shot groups and the smallest was .265" and the largest was .35 inches. I only fired two groups with each but, lordy! that was enough! This rifle is not fussy as long as the bullet sits over H322 powder. It could be my new favorite .223 fodder. Amazing.~Muir