The MCX Rattler is the most compact MCX variant, featuring a 5.5-inch barrel in 300 Blackout and a folding Rattler stock, designed as the most portable suppressor host in the SIG lineup for close-quarters operations. Type: Semi-Auto Rifle Action: Gas-Operated Caliber: 300 Blackout Capacity: 30 Year introduced: 2017, USA Weight: 4.9 oz Overall length: 16" Status: Active Intended use: Suppressor Host, NFA/SBR, Special Operations, PDW, Suppressed Shooting, Tactical, Home Defense