The Hiperfire Enhanced Duty AR-10 Heavy Gunner Trigger is a single stage trigger designed with additional hammer mass for the larger .308 round the AR-10 uses. The Heavy Gunner Trigger includes two springs for the user to choose a 4.5 or 5.5 lb pull weight. The MIL ++ Heavy Duty Hammer Springs are designed for a hard hammer strike and a crisp, clean break with little over-travel and a positive reset for the shooter. Easy installation and a huge upgrade over the Mil-Spec trigger. Made in the USA.