Well, the best ammo would be rolling your own-at least for the money and if you are careful, the accuracy as well. So far as store bought, Federal match ammo 168 grain is one of the most respected, along with similar ammo from Black Hills.
500 yards is a fair piece, and you might see better results from 175 grain match loads. I'd buy a box of Federal, Black Hills, Hornady and a few others and see which groups the best in your rifle.
Had the same question about my Remington VS in 308-turns out the most accurate I could buy was Remington Match-fancy that! Does not mean the ammo made by the same name is always going to be best, but it does happen.