Introduced in 1857 the First Model was manufactured in various forms through 1881 with this being an example of a First Issue 5th Type (rifling changed from three grooves to five). The top of the barrel rib is marked with the one line address with 7-shot non-fluted cylinder and grips numbered to the gun.

This is an example of a 6th Type, the last First Issue variation (rotating recoil device eliminated and instead a ratchet was made integral part of the cylinder). The top of the barrel rib is marked with the one line address and the patent date is stamped on the 7-shot non-fluted cylinder. The right grip panel is numbered to the gun.