Sorry, I don't buy your explanation at all. The picture is the effect of the camera flash and the shutter speed and the distance the camera was from the pistol when this picture was taken. The light from the flash hit the pistol just before the hammer struck the firing pin. Immediately after the light reflected off of the pistol, the cartridge fired, the bullet left the barrel, and the light generated from the flame from the hot gases that propelled the bullet followed directly behind the light from the flash that reflected off the pistol and a portion of that light from the hot gasses entered the aperture before the shutter closed. The hammer appears back because that was the position of the hammer when the light from the flash reflected off of it. The light from the hot gasses of the burnt powder happened immediately after, but a portion of that light made it past the shutter before it closed.
All in all, a well timed photo. Bravo, probably one in a million from a standard camera setup!