Hornady Superformance, 308 Winchester, 150 Grain, Copper Alloy eXpanding Projectile, 20 Round Box 80944 Increase your rifle's performance up to 200 fps without extra chamber pressure, recoil, muzzle blast, temperature sensitivity, fouling, or loss of accuracy. Superformance uses progressive propellants that take your favorite V-MAX, NTX, SST, CX, and InterLock, bullets to levels of performance that are simply unattainable with conventional ammunition.