Trust me, a pair of Colts or even one will still kill as well as they did back in the day. We are no more bullet proof than back then!
We are not any more bullet proof, but we are harder to kill- we weigh considerably more now, and have much better medical care.
a .36 roundball weighs what? 95grains? At 7-800 f/sec? 1000, even? and you have five shots?
You empty that into a big determined individual and you might kill him .... after he beats you to death with your "gun".