What he probably meant was he had to adjust his scope up 12 moa to shoot at 500m. A moa is a minute of angle equivelant to 1.047" at 100 yds, but most simply drom the decimals and say 1MOA is 1" at 100yds... 2" at 200yds, 3" at 300yds and so on. In this instance, 12moa X 500yds equals 60" of adjustment, a bit much for this combo at that distance... but possible depending on the particulars. There are other possibilities, but this one is the most likley.
Man, I must a been typing slow!!!