CMMG 60AB40CAB: The 6mm ARC (Advanced Rifle Cartridge) was designed to deliver excellent ballistic performance in AR15 platform rifles that rivals the extended range performance of larger rounds typically chambered in the larger AR10/LR308 style rifles. The combination of our Br4 platform which delivers little recoil, and this flat shooting round makes a great choice for hunters and extended target shooters looking for predictable performance. Comes with (2) CMMG 10rd magazines.