Sub‑X® (Subsonic — eXpanding) bullets deliver big results without a big bang! Designed to provide deep penetration below the speed of sound, Sub‑X® features a lead core. Long grooves in its gilding metal jacket combine with its flat profile and the patented Flex Tip® insert within the bullet’s hollowpoint cavity to help it expand reliably at low velocities. Cannelures provide positive case crimp, making Sub‑X® ideal for semiautomatic firearms.