My RRA Predator Pursuit (16" barrel, 1:8 twist) absolutely loves Hornady Superformance Varmint 53 gr. V-Max ammo. I can consistently shoot nickel-size groups at a 100 yards with it. I'm very pleased with it!
I use to run their 55 gr. varmint load with good success; however, the new Superformance stuff is much more accurate out of my rifle.
I've also tried some heavier weight factory ammo (e.g., Black Hills 60 gr.), but the results were less than favorable.