I was finally able to get out and shoot my Springfield Armory Saint Victor 5.56 AR the other day. Was very pleased with the functionality, it fed and functioned well. I was trying to zero my Aimpoint PRO optic. I was zeroing with Winchester M193 55 grain FMJ ammo. At 25 yards it was fine, but at 50 yards it was abysmal. Horrible groups. I know that each barrel likes different ammunition, but there are also certain brands/loads that are constantly more accurate with certain rifles. Does anyone have any experience with AR`s and 5.56 ammunition, and specifically, what brands have a history of being most accurate in AR platform rifles?