Most of the improvements that distinguish this model from First Model are internal and not readily apparent. Most obvious external change is the rectangular cylinder-stop notches. This model is serial numbered from 8000-10700. Total production of approximately 2,700 revolvers manufactured in 1850 and 1851. There is a Civilian Model, Military Model and an extremely rare variation that was issued to the militias of New Hampshire and Massachusetts (marked \MS.\")."