Whether you're a high-volume AR shooter or love to build your rifles from scratch, the Bravo Company Manufacturing Standard 5.56 NATO Upper Receiver Group with MCMR-15 Handguard offers quality MIL-SPEC features ideal for all shooters.Features: 5.56 NATO chamber 20" Mil-B-11595E steel barrel Cold hammer-forged barrel Manganese phosphate barrel finish M4 feed ramp barrel extension T-marked upper receiver USGI 1:7 twist rate Chrome bore and chamber 3" Picatinny rail section BCM MCMR sling mount