A two-stage trigger assembly for the M16 or AR15 weapon systems. The trigger assembly comprises a spring loaded hammer, trigger and disconnector. Calibrated springs are provided to facilitate the adjustment of the second stage trigger pull weight. No set screws adjustments are necessary and a secondary safety sear similar to the factory original fire control components has been incorporated to prevent the unintentional mechanical discharge of the firearm. Installation of the disclosed device is identical to the factory fire control group and requires no hand fitting.