HORNADY MFG CO Superformance SST6.5 Creedmoor, SST, 129 GR, 20 Rd/bx Superformance is a cutting edge technological advancement in ammunition design that transcends convention and achieves the highest performance of any ammunition on the market today. 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 with 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 usable energy to the bullet reducing the rocket nozzle effect at the muzzle while still increasing velocity! Superformance provides increased performance, and is safe to use in all firearms, including semi-autos, lever gun and pump actions. Increases in rifle performance, no increases in barrel wear and felt recoil, along with superior temperature stability are all realized with Superformance ammunition. It really is Rocket Science. Features a streamlined for ultra-flat trajectories. Polymer tip for rapid expansion and maximum energy transfer. Match-grade jacket delivers surgical accuracy. Heavy construction with InterLock® feature delivers deep penetration every time.