Developed for military and law enforcement applications, these bullets feature a frangible, powdered-metal copper-tin core. What sets these bullets apart from other frangible projectiles is their gilding metal jacket, which keeps the bullets intact during rough handling, feeding and firing. This, in turn, reduces gun jamming occurrences from prematurely fragmenting bullets. Notes:Designed for use in M4, HK416 and other AR-15 firearms with a 1 in 9" or faster twist rateATTENTION RESIDENTS OF THE STATE OF CALIFORNIA:This bullet is certified by the State of California to be in compliance with the California Lead-Free Ban and meets the criteria under the Condor Preservation Act.