Sir.
You have good taste in shotguns and handguns. I live in a poorer neighborhood.
I find a 870 Remington with a short barrel to suit my needs.
Especially when dealing with long legged snakes. When the snake is longer than the shotgun, shoot twice.
For a handgun on snakes I have used a Model 28 several times.
I think your concept is a sound one though. 12 gauge or .357 Magnum. I don't know what you use yours for but down here the snakes don't really complain no matter which I use.
Bill@Yuma