I've had a box of shot shells for a .38/.357 for years but have never used them, mainly because I live in the suburbs and though I have seen more wildlife than anywhere I've ever lived, shooting is frowned upon. I believe the little box only has about a dozen rounds.
An excellent article appeared in a gun magazine probably 15 or 20 years ago, written by a guy who lived in Florida and who though the S&W Model 66 with a 2 1/2-inch barrel was the best possible carry gun. He was a guide and habitually carried two rounds of shot loads for snakes, which he often saw out in the woods. But he also said that the shot loads didn't seem to work on a swimming snake, so his revolver was also loaded with .38 wadcutters, which did work. He also used 125-grain magnum loads and claimed everything shot to the same point of aim.
My father seemed to be killing snakes a lot where he lived in West Virginia but he used an ordinary .22 revolver.
Shoot low, sheriff. They're riding Shetlands!
Underneath the starry flag, civilize 'em with a Krag,
and return us to our own beloved homes!
Buy War Bonds.