Timney AR-15 Drop-In Skeletonized Trigger 4 lb. #664S - Small Pin

The Timney AR-15 Drop-In Skeletonized Trigger 4 lb. #664S with small pin is a factory-preset, true drop-in trigger assembly designed for direct installation into standard AR-pattern rifles without modification or adjustment. The 4-pound pull weight delivers a crisp, clean break ideal for precision shooting, range training, and tactical applications where trigger consistency matters. Installation requires no gunsmithing—the trigger module uses your rifle's original hammer and trigger pins, eliminating compatibility concerns common with aftermarket options.

The skeletonized design reduces overall weight while maintaining structural rigidity. Timney's proprietary trigger geometry prevents pin rotation and walkout, a common failure mode in standard triggers under heavy use. The small-pin configuration (664S designation) is compatible with mil-spec AR lowers and direct-impingement platforms. For users running polymer lowers, Timney recommends backing the trigger with a thin aluminum shim to distribute contact pressure and prevent creep or deformation over extended shooting periods—a detail that distinguishes field-experienced designs from theoretical specs.

This trigger suits law enforcement, military trainers, competitive shooters, and serious enthusiasts who prioritize repeatable trigger performance without removing the lower receiver. The 4-pound break is light enough for accuracy-focused work yet heavy enough to meet standard duty and training protocols. Unlike triggers requiring adjustment or proprietary lower receivers, the 664S integrates seamlessly into existing platforms, making it an accessible upgrade for operators building or refining multi-purpose carbines.

Timney triggers are recognized for consistent quality and reliability in precision and duty applications. The combination of drop-in simplicity, verified pull weight, and proven pin-retention design makes this an efficient choice for anyone seeking to improve trigger performance without extended downtime or technical complexity.