They are a lot of fun and the Uberti should do you well.
Keep in mind these are not as well made as a modern gun, not sure if its the market or what, but you can and do get them with various annoyances as far as function goes. The last two I got were good (sans shooting too darned high). Some are miner and some don't work at all.
Still a bit puzzled with can you trust your life with one. They are not good guns for that vs a modern cartridge revolver and I would not be keen on trusting my life with anything. Have to is a different story, lots of times had to do the best I could with what I had (not gun fights)
As for manstopper, that is a ????? They will kill people, not reliably, as I recall one Western gunfighter or law enforcement was shot 20 some times over his career and lived. He had to have had one fantastic immune system in the face of infection alone. Some people get shot and quit and some people get shot and don't. You are not allowed to see a I got shot resume before it happens (usually).
You want a reliable manstopper, then we are talking 20mm cannon. People survive rifle shots and die when hit in the wrong place by a 22. You have to take out a critical function to kill something. Its a reason you don't want to stare down a charging grizzly. It may wander off and die after it chews you up or kills you. Other than maybe some consolation to your family, well it ain't no consolation to you (well George took out that man killer griz and died for humanity).
I know of a a shootout (and digging deep into memory, two troops vs a nut job). The nut job was hit with 4-5 357 Mag rounds as well as something around half a dozen to 8 x 9mm. The last 9mm knicked an aorta and he bled out.
The trooper with the 357 magnum was in uniform and was targeted. I forget what he got hit with from the nut job, rifle of some kind as I recall, but it was a number of rounds. He lived but was so badly wounded he could never return to work.
Now a 20mm cannon takes out a pretty good sized chunk so odds are you get hit anywhere with it and you are kaput (grazed not so much). Hit an arm and its gone. Chest hit, phew. 50 cal? Those are semi armor piercing if not AP, it can go through you as well.
I shot 4 Caribou back when I was hunting. 7mm cooking along at close to 3000 FPS and 175 gr bullet (could have been a tad lighter). Danged if it did NOT knock them off their feet. Killed em cause they were good heart lung shots but sure did not knock them down despite surprising them.
Bottom line is modern SD ammo is your best chance and better yet is hope not to be there in the first place.
