The .50 Caliber Umarex Hammer is not just some pellet rifle. The Hammer delivers serious big game hunting power and needs serious ammo for the job. At 550 grains in weight, the UX SLA hard cast slug is the hard-hitting answer for the most robust game animals around. When launched from the full regulated pressure of the Hammer this .510 diameter slug will be flying at about 790 FPS and delivering near 760 ft-lbs of energy at the muzzle.