When compared to the standard AR15 model, the AR-9’s hammer design has more mass, which in turn has more inertia. The AR-9’s center of percussion is also lower than that of the AR15’s. The result of these two factors is maximum energy being transferred from the hammer into the firing pin and thus more reliable primer strikes. Available in straight or curved. About TiggerTech's Pistol Caliber Carbine TriggersTriggerTech’s line of Pistol Caliber Carbine Triggers were built for competition shooters who needed the most precise and reliable triggers available. These triggers were made to feel like that of a 1911, with a short overtravel and a two-stage action. In addition, the Pistol Caliber Carbine Triggers utilize Zero Creep Technology which doesn’t rely on coating or lubrication, so each trigger pull will be just as consistent as the last. TriggerTech AR-9 Two Stage Competitive Curved Black 3.5 lbs Trigger AR9-TBB-33-NNC