Sear mechanism for a firearm

What is this patent about?

’504 is related to the field of firearm trigger mechanisms, specifically sear assemblies designed to provide a consistent and precise two-stage trigger pull. In high-performance shooting, the tactile feedback and predictability of the hammer release are critical for accuracy; however, traditional manufacturing often results in surface irregularities that lead to a gritty or unpredictable trigger feel.

The underlying idea behind ’504 is that the geometry and surface finish of the critical engagement points—specifically where the trigger sear, disconnector, and hammer interact—can be optimized by using electric discharge machining (EDM) on an intermediate workpiece. By incorporating specialized processing apertures directly into the trigger element's design, a wire EDM can precisely cut ultra-smooth contact surfaces that ensure perfectly flat surface-to-surface engagement, which is otherwise difficult to achieve through standard casting or forging.

The claims of ’504 focus on a sear mechanism featuring a trigger element with integrated processing apertures located adjacent to the sear contact surface or the disconnector pad. These apertures serve as the entry or guide points for the EDM wire during manufacturing, allowing for the creation of a high-precision sear contact surface and a disconnector pad that dictates the exact timing and weight of the two-stage release.

In practice, the invention functions as a modular drop-in unit where the trigger element and disconnector are independently pivotable on a shared support pin. During the first stage of the pull, the trigger and disconnector move together against spring resistance until the hammer sear hits a contact face on the disconnector; at this transition point, the shooter feels a distinct increase in resistance. The second stage then requires only a slight additional force to slide the hammer sear off the precision-machined trigger sear, resulting in a crisp, predictable break.

This approach differs from prior solutions by moving away from the 'hit-or-miss' tolerances of cast parts or the manual polishing of engagement surfaces. By utilizing wire EDM paths enabled by the specific placement of processing holes, the invention ensures that the critical sear geometry is repeatable and immune to the slight dimensional deviations that typically cause uneven trigger pull weights. This results in a mechanical interface that provides a smooth take-up and a sharp release, significantly enhancing the shooter's control over the firearm.