When I lived in Oklahoma, I often carried a little derringer that was .22 on top and .410 below. A .410 shotshell will definitely do in a snake and I would recommend a .45/.410 handgun for snakes, but the question was about CCI shotshells. A Taurus or S&W .410 revolver is a pretty substantial investment and for some it might be much more practical to use shotshells in an existing firearm. Heck, if I were going to buy something specifically for snake protection, I'd probably get a .410 double-barreled shotgun with short barrels. It doesn't weigh much and it will definitely throw a more predictable pattern than anything with rifling in the barrel.