JP Enterprises Enhanced Reliability Spring Kit 3.5-4.0 lb Trigger Pull A AR-15 Fire Control A Low-Sensitivity Primer Compatible A JPS3.5T The JP Enhanced Reliability Spring Kit yields a 3.5-4.0 lb trigger pull when used with JP fire control parts. Intended for use with JP trigger components-will not necessarily produce substantial change on standard AR-15 trigger components. Allows reliable ignition of ammunition with low-sensitivity primers such as those found in NATO-spec and various foreign-manufactured ammunition. For large-frame ARs and duty/defense rifles, domestic-manufactured ammunition is strongly recommended to ensure 100% ignition reliability. Compatible with most component-style AR fire control systems. Not compatible with the JPFC-M modular trigger. SKU: JPS3.5T. 3.5-4.0 lb Trigger Pull Yields 3.5-4.0 lb trigger pull weight when used with JP fire control parts. Provides a slightly heavier pull than the lightest JP spring kits for improved primer ignition reliability. Low-Sensitivity Primer Compatibility Allows reliable ignition of low-sensitivity primers found in NATO-spec and various foreign-manufactured ammunition. For duty, defense, and large-frame AR applications, domestic-manufactured ammunition is strongly recommended to ensure 100% ignition reliability. Compatibility Compatible with most component-style AR fire control systems. Not compatible with the JPFC-M modular trigger. Intended for use with JP trigger parts-results on standard AR-15 trigger components will vary. Specifications: Manufacturer: JP Enterprises Model: Enhanced Reliability Spring Kit SKU: JPS3.5T Trigger Pull (with JP fire control): 3.5-4.0 lbs Intended Use: JP Fire Control Parts Compatible: Most Component-Style AR Fire Control Systems Incompatible: JPFC-M Modular Trigger Application: Low-sensitivity primer ammunition (NATO-spec, foreign manufacture)