JP Enhanced Reliability Spring KitThis spring kit will yield a 3.5-4.0 lb. trigger pull with JP Fire Control parts. This kit is intended for use with JP trigger parts and will not necessarily yield substantial change on standard AR-15 trigger components. Application: Use of this spring kit allows for use of ammunition with low-sensitivity primers such as those found in NATO-spec and various foreign-manufactured ammunitions, but in the case of large-frame ARs and duty/defense rifles, domestic-manufactured ammo is strongly recommended to ensure 100% ignition reliability.