One of the other fallacies involved in the "It does the job every bit as well today as it did in 1851" is that in 1851 everybody was playing with the same deck of cards.
Everybody was subject to the same liabilities, vulnerabilities, and weaknesses of the percussion guns.
In other words- a more or less level playing field, as far as technology went.
The same, in 1851, could be said of a sword- "It cuts every bit as well today as it did in 1061."
But, in 1061 when EVERYBODY had a sword, with its own vulnerabilities, it was much more of a level playing field then, too.
In 1851 nobody was saying "I like swords, I don't care that a man with a modern .36 Navy can kill me before I can even get close enough to use my sword, I'm going to carry it anyway."
Those who understood the risks & the needs, and took them very seriously, used the most modern technology available.
You didn't see Hickok carrying a sword, you saw him carrying what was, at THAT time, one of the best-carrying (or two of them, anyway) belt guns available in terms of controllable power, weight, and proven (as far as percussions could be proven) reliability.
You can safely bet, had he lived more than three years beyond the Colt Peacemaker's introduction, he would have eventually switched over to more power, more reliable metallic cartridges, and the quicker reloading of the Colt .45.
As it was, you notice he did carry TWO .36s, and that wasn't just to balance out his stylish ensemble.
He knew their limitations, and he didn't yet entirely trust the new self-contained cartridge guns. There were many others who didn't either & kept on with percussions for years after the metallic cartridges became established in handguns.
If you should ever need to defend yourself, and the other side has a gun, you'll most likely find yourself with the 1851 equivalent of taking a sword to a gunfight.
All this is not to mention the .380 (and the .36) can both be quite survivable with modern medicine. One important part of the gunshot mortality rate of the percussion era was the primitive medical services available then, not necessarily the immediate incapacitation power of the .36s & below.
And, before you bring up the "Placement Is Everything" mantra, I'll say it isn't always, doesn't guarantee immediate incapacitation unless it's a CNS or head strike, and even then you'd better be damned good with your 6 against a moving target that's probably shooting back at you.
I didn't use the "stupid" word & I'm not using it.
Deliberate handicap is the term I'm using.
If that's acceptable to you, by all means, go for it.
Denis