I'll offer this - modern comparisons here aren't going to be valid, so let's stick to what the original post was about, and dial it back a bunch of decades...
When men get shot - whether it be from a .22 of some variety, or something larger, there's one thing no one's really factored in, and that's the complete and utter shock that screams in the brain and says - 'I've been SHOT!!!'
This isn't 'shock' as in displacement of fluids, or making the target do cheetah flips, as in a John Woo movie - this is the mental shock that says to the brain that 'something' is wrong, something has penetrated me, something is making me bleed, it hurts - all coupled up into the disbelief that it just all went sideways, and I don't know quite how...
Believe me, 'that' is shock - and that type of shock kills just as quickly as a well-placed round does, because I've seen it happen.
Training and self-preservation and anger all play their parts in a hurry, and make men respond, but that's not the point - the point is that it takes very little to kill a man, and when factoring in the psychological effects that further debilitate him - it takes even less, because for 'some' men, it further weakens their resolve - essentially dooming them.
Getting shot 'hurts' - trust me on this - it refocuses one's attention a bit, unless the action around one is so intense that it goes un-noticed until later, and on the battlefield, wounding a man is preferable, because it removes him 'and' usually two of his buddies from the fight that opt to tend to him, because in today's world, it's the humane thing to do, and it's expected, so many will stop their fight right then and there and wait.
The movies and Westerns are replete with gunfights that never happened, but if the true activities of the times were recounted, no one would go to the movies or read a novel just to learn more about 'Those Thrilling Days Of Yesteryear' - watching crops get planted, and driving freight.
In answer to the original question - 'yes' - the round was effective when fired from a revolver, 'if' it connected...
It had to do 'that', first - and despite the many, many novels, most cowboys weren't crack shots with either hand - that's why they used long guns.
At close range, that slow, fat, lead round - even if it didn't penetrate a Buffalo coat completely - could transmit enough force to get the other guy to stop what he was doing long enough to take better aim, and maybe re-think his life's choices.
The round stayed in production a long time - and several that would follow shared very similar ballistics, so it would seem to've been bot popular and effective, otherwise it would not have kept filling cylinders.
So - this conversation has pretty well run its course, but it's still Winter, and some are still cabin-bound, so I'm certain something else will spark someone's imagination.
Scouts Out!