Simple....



1 MOA = 1" @ 100 yards (well, technically it's 1.0472" but common acceptance is 1")
or 2" @ 200 yards
or 3" @ 300 yards
or 4" @ 400 yards
...see where this is going?

So if your rifle shoots a .75" group at 100 yards, that's 3/4 MOA. Theoretically, the rifle should be capable of maintaining that same 3/4 MOA at any reasonable distance for the cartridge/bullet combination. If we're talking 1,000 yards it would be a 7.5" group. Of course this assumes that the shooter remains consistent with his part of the accuracy equation as the distance increases and is adeptly skilled at reading and adjusting for the conditions.