Other gunscribes have compared the ballistics of a Colt's Navy to those of a modern .380, rather than a 9.
The 'pair of Navies, in his sash' seems pretty standard; it's either true, or has been repeated enough that it's thought to be true.
I'll opine that a Walker seems unlikely, as a belt gun...they are a big sonafagun, and were normally carried in pommel holsters, rather than belt rigs. Dragoons aren't much better.
Again, the Navy was noted as the 'gunfighters' gun' for its relative handiness, compared to contemporary .44 revolvers.
Have a .36, and it does have a wonderful feel in the hand.
By the time of Hickok's death, cartridge arms were extant, though it's not clear to me how universally the guns, or their cartridges, were available in 1876. That Hickok was carrying a cartridge Smith at the time of his death, isn't surprising.
Interesting discussion.
Moon