The MCX Rattler in .300 BLK is the most compact MCX variant, using a 5.5-inch barrel and ultra-compact pistol brace, designed as a suppressor host and home defense option. Type: Pistol Action: Semi-Automatic Caliber: .300 BLK Capacity: 30 Year introduced: 2018, USA Weight: 86 oz Overall length: 17" Status: Active Intended use: Suppressor Host, Home Defense, Tactical