7.62 x 51 nato

I know i'll probably get hate because this is been asked probably a million plus times, but I haven't found a definitive answer yet. Which is better to shoot from an M1A? I know both will shoot just fine in the M1A. I'm asking because I want to know which will cause the gun to have more wear...

I've got 900 rnds of 7.62 x 51 NATO made by CAVIM for sale, $ 400 plus shipping OBO. Its '93 or so manufacture, fully annealed, non-corrosive and boxer primed (re-loadable) in 20 rnd boxes, 5 boxes per sleeve. I've had good success with this ammo. I'm in Indiana and am presuming I can ship it...