Accepting Sig M17/P320 magazines, the CMMG Mk17 Banshee 300 delivers a new level of performance to the PCC world. The Mk17 brings out all the features you've come to expect from CMMG, including last round bolt hold open. Its Radial delayed blowback operating system guarantees less felt recoil, which means faster up shots and a more enjoyable shooting experience.