Does anybody know if the hammer on the New Vaquero will "drop in" an Old Vaquero frame? I know there are differences in the frames, just don't know if those differences would make the swap impossible or not.
It is not drop in. The hammer skirt will have to be ground down a bit to match the profile of the regular hammer. The same thing you have to do on a Bisley hammer, just less to remove. Also, the transfer bar is thicker on the New Vaquero so you will need to use the New Vaquero transfer bar or file some of the top step off to get enough firing pin protrusion.