The overall length is very important, as they must fit the pistol's cylinder.

First, let's see how they work on snakes.

Here's a target and we will be shooting at around 8 feet with the .38 Special out of a snub nosed revolver.

As the shot capsule goes down the barrel, the rifling tears the plastic capsule and it comes to pieces upon exiting the barrel.

Here's the result on the target.

Looks like 17 hits, counting the base plug.

Then we will try the .44 Magnum out of my S&W Dirty Harry pistol.

Same distance, 8 feet.

It did a fine job.

49 hits, plus the base plug.
I can tell you from experience that a snake shot with these rounds is a dead snake.

And with the .44 Magnum shotshells, the snake looks like it was run over by a Big Mac truck.

But how deeply do they penetrate?

Even big Texas rattlers are usually not more than a couple or three inches thick, and their vital organs are only an inch or so deep.