Hornady(R) Subsonic Ammunition - designed for accuracy and performance below the speed of sound. The Sub-X bullet used in Subsonic Rifle features a lead core. Long grooves in its gilding metal jacket combine with the bullet's flat profile and the patented Flex Tip(R) insert within its hollowpoint cavity to help it expand reliably at low velocities. Powders are selected for optimal performance and consistency from lot to lot.