Hornady Subsonic Ammunition is designed for accuracy and performance below the speed of sound. The Sub-X (Subsonic - eXpanding) bullet features a lead core. Long grooves in its gilding metal jacket combine with the bullet's flat profile and the patented Flex Tip insert within its hollow-point cavity to help it expand reliably at low velocities. Performance of the Hornady Subsonic load meets or exceeds FBI Protocol terminal ballistic test requirements. FeaturesLoaded with unique powders optimized for subsonic use, the low flash signature is ideal for both suppressed and unsuppressed performanceBullets feature a cannelure for a positive case crimp for use in semi-autosDesigned specifically to fit, feed, and function in a variety of firearms including gas system guns