I agree it can't be a Colt, since the position and shape of the cylinder release clearly indicates a S&W type. K or J frame is hard to tell as the proportion depends on the guy's relative size. I think he actually has the hammer cocked and the finger back on the trigger, skewing the appearance a bit.

The thing in his left hand appears to be just the holster part of an old-fashioned leather shoulder rig wirh the metal buckles to attach the straps.