Caliber 9x19mm – Operating system Roller- delayed Blowback Proven reliable – Action Semi Auto – Barrel 8.86 3 Lug Nitride treated – Twist Rate 1/10 – Length 17.6 – Weight 5.05lbs – Trigger Pull 9-10 Lbs – Handguard Aluminum M-lok – Aluminum Picatinny Optic Rail – End Cap Black Polymer with Sling Swivel – Original Style Paddle Style and Push Button Mag Release – Magazine 30 Round accepts standard Milspec MP5 Magazines