The Winchester crimped shotshells have always performed better for me than the CCI capsule form.
I've used these successfully on mice and rats on a pig farm, so as not to risk harm near the animals. Pretty anemic, though. I've seen rats jump and run after being shot at well under 10 feet. I'm certain they died, but not DRT.
I've shot snakes in the past with them, and it is successful at making them curl up for a follow up shot. I took a 4 foot hognose from the front porch last summer; he was curled up in a rubber tree, taking goldfinches from the feeder. He had 3 in his belly.
However, if you remove all the snakes, you're going to have lots and lots of rats, gophers, moles, voles, and other rodents.
Since experiencing this in the past, I only kill a snake if it's an immediate danger to myself, family, or animals. If it's not close enough for a shotshell, you're hardly in danger. Usually, if you're already outside working, the shovel/rake/weedwhacker/lawnmower you are using is already enough tool for the job.
I've never seen it have enough blowback to cycle an autoloader. Revolvers are the best tool for shotshells.
EDIT: This only refers to .22LR shotshells, I've never used any of the larger caliber shotshells. If it's something that big, a shotgun might be the right tool. And if the snake is that big, I'm skeered.