I'll add that when you see the term MOA used on this forum, its usually someone talking about their bullet groupings on the target. So if they say "I can shoot MOA" (or sub-MOA), they basically mean that their group of shots are landing within a 1" group @ 100 yards (2" group @ 200 yards, 3" group @ 300 yards, etc). If your groupings is 4" @ 100 yards, then that's 4 MOA. That's all accepting 1" @ 100 yards as MOA.