Hickok was known to have owned a number of different pistols, including I believe an 1860 Army Colt, and at least one S&W .44 cartridge pistol, I believe a single action American model, a top break with an 8" barrel. I believe he simply liked the Navies, and their feel, and shot them well. As to their power level, comparing them to a 380 may not be entirely accurate. Keith wrote of talking with Civil war vets and others that had used various pistols in fights, and they generally thought tha Navy was a decent fighting pistol for it's day, even comparing it to the 38 spl 158 gr
RNL load, and feeling that the stopping power was superior to
that load. Notice I did
not say "any load ever made" for the 38 spl. The old 158 gr RN lead load didnt enjoy a very good reputation for stopping power. The difference was most liekly, as Keith mentioned, that the 36 cal soft lead ball, while lighter, tended to deform like a hollow point does, and make a more serious wound than a harder RN bullet. This was a well known phenomenon back in the day, and the round ball was generally thought a better stopper on men than the conical bullets available for the 36, tho the latter had better penetration.
There are also known pictures of Hickok carrying pistols in holsters. Because he carried his pistols in one particular way at one time doesnt mean thats the only way he ever carried them. Same as the Navies themselves. They are what he's best knwon for, but he also was known to have owned, and used various guns over time. I believe in the Tuttle fight he used either an 1860 or a Dragoon, I don't recall which.
I for one, also believe that Hickok may have had more than the one pair of Colts Navies, just as many serious shooters today, and over time, have had a number of guns, and spares.