CMMG starts every project with one of the most popular AR-15 calibers in mind, the 5.56. The Br4, was no different and was designed for Americans residing in states with restrictions a lot of us can't comprehend or relate to. Now introducing the Br4 with an all-new EMPIRE profile unthreaded barrel and a recessed barrel crown. As if this new Br4 platform wasn't good enough, CMMG found low hanging fruit for states that don't allow threaded barrels. Like the entire Br4 lineup, this upper group compliments the firearm nicely and a lower group that accepts 5.56 AR mags.The 16.1" firearm ships with (2) 10rd Magpul PMags, Remington 870 stock compatible, cross-bolt safety, forward non-reciprocating side charger, a proprietary Zeroed single stage trigger and your choice of (7) colors.