Bi-directional trigger

What is this patent about?

’066 is related to the field of firearm trigger mechanisms, specifically semi-automatic fire control groups. It addresses the technical challenge of increasing the rate of fire in platforms like the AR-15 without resorting to fully automatic configurations or external sliding stocks. The background context involves the standard cycling of a hammer and disconnector, where a single trigger pull typically results in only one discharge, followed by a reset phase that requires the user to release the trigger before firing again.

The underlying idea behind ’066 is to achieve a discharge on both the rearward pull and the forward release of the trigger by precisely modifying the geometry of the disconnector and the fire selector. By significantly shortening the hammer hook and deepening the selector recess, the system allows the hammer to slip past the disconnector earlier during the trigger’s return stroke. This timing shift ensures the hammer is released to strike the firing pin upon trigger return rather than being caught by the trigger’s primary sear, effectively doubling the potential rate of fire through mechanical timing.

The claims of ’066 focus on a specific set of geometric ratios within the fire control group that enable this bi-directional operation. Specifically, the independent claims protect a trigger disconnector where the ratio of the hammer hook attachment length to the hammer hook length is approximately 5.46. Additionally, the claims define a fire selector where the ratio of the external diameter of the operational portion to the depth of the fire control recess is approximately 2.2. These specific proportions are the mechanical constraints that allow the hammer to bypass the standard reset cycle.

In practice, when the user pulls the trigger, the firearm discharges normally, and the recoiling bolt carrier pushes the hammer back into a cocked position where it is held by the disconnector. As the user begins to release the trigger, the shortened hook on the disconnector disengages from the hammer lip much sooner than in a standard configuration. Because the fire selector features a deeper fire control recess, the trigger can travel through a wider arc, preventing the forward sear of the trigger from catching the hammer as it is released by the disconnector, resulting in a second discharge.

This approach differs from prior art by achieving high-speed fire through internal component geometry rather than external aids like bump stocks. Unlike standard semi-automatic triggers that have a hook-to-attachment ratio of roughly 2.857, the ’066 invention utilizes a 191% increase in this ratio to fundamentally alter the release timing. This allows the firearm to remain compliant with regulations requiring a single discrete action for each discharge—treating the pull and the release as two separate trigger functions—while providing the shooter with a rate of fire comparable to automatic systems.