Help with ID of a strange flare/signal pistol

[somd_mustangs]

This one is pretty weird. It has some sort of guide pin at the front of the frame (it's not just a nail, it's a hardened pin with a machined end) and a needle firing pin. You manually pull back the cocking knob to fire, and the flare (or whatever) is loaded from the muzzle and held in place by a clip. The grips look like a "C" is incorporated around the screw. It uses roll pins and hex set screws so it's fairly modern I believe. Overall size is relatively small, and bore is ~3/4", a 12 ga round just barely won't fit.