Hornady .270 Winchester 130grn SST Superformance Rifle Ammunition. Superformance uses ultra progressive propellants that take your favorite SST or GMX bullets to levels of performance that are simply unattainable with conventional propellants. In order to get more velocity in the past – shooters have used a brute force approach – large charge weights of a slow burning powder in a larger cartridge case. Ultimately this leads to more recoil and muzzle blast. The Superformance solution is an elegant approach that utilizes specialized powders…at NORMAL charge weights, that impart ALL useable energy to the bullet reducing the ROCKET NOZZLE EFFECT at the muzzle while still increasing velocity! Packed 20rds to a box, 200rds (10 boxes) to a case.