Description Increase you favorite rifleâs performance by up to 200 fps without extra chamber pressure, recoil, muzzle blast, temperature sensitivity, fouling, or loss of accuracy. Superformance uses ultra progressive propellants that take your favorite SST and GMX bullets to levels of performance that are simply unattainable with converntional propellants.PRODUCT DETAIL:Caliber: 270 Winchester Grain: 140 Bullet: SST Per 20 Muzzle Velocity: 3090 fps Firearms, trailers, and some accessories are only available for purchase in stores. Each location follows all BATF and individual state/county/city laws to insure the desired product is legal for sale. Any info provided online is subject to change, please go to your local store for more accurate information.