The BANSHEE 300 5.7x28mm upper receiver has a 5-inch barrel and features CMMG�s patented Radial Delayed Blowback operating system. The receiver and hand guard are hard coat anodized and come with a pre-installed CMMG Ambi Charging Handle and a CMMG RML4 M-LOK Hand Guard. This package ships with three 40-round 5.7 AR Conversion Magazines. - All of our Upper Groups come complete with BCG - TECH SPECS: - CALIBER: 5.7x28mm - BARREL: 5� 1:9 Twist Medium Taper 416SS - MUZZLE: Thread Protector threaded 1/2-28 - RECEIVER: Forged 7075-T6 AL M4 type upper - HAND GUARD: CMMG RML4 M-Lok hand guard - FINISH: Hard Coat Anodized Receivers and Hand Guard (Can be upgraded to Cerakote) - CHARGING HANDLE: CMMG Oversized Ambi - MAGAZINE: CMMG 40Rd x3