Pneumatic gun having mechanically-actuated pneumatic valve

According to principles of the present inventive concepts, a mechanically-actuated pneumatic valve can comprise an input port receiving compressed gas from a compressed gas regulator and one or more output ports. A face seal can be arranged in the valve body and be configured to move between two positions. In a first position, the face seal can permit compressed gas from the input port to be supplied to a first output port. In a second position, the face seal can vent compressed gas from the valve body through an exhaust port. An actuator, such as a pin or pin-shaped actuator, for example, can be configured and arranged to move the face seal from the first position to the second position, such as during a trigger pull. A contact surface could be configured to physically contact a surface of the pin-shaped actuator (either directly from the trigger or through one or more other components or mechanisms) and drive the face seal to its second position during actuation of the trigger.