With subsonic and supersonic loadings available for self-defense, hunting, and target shooting, 300BLK is one of the most adaptable cartridges out there today. No matter how you plan to use your Br4, this .30 cal carbine packs practicality, like the full length top Picatinny rail and M-LOK handguard, with unmatched style. Comes with (2) Magpul 10rd PMAG.