Growing up on the farm we shot countless rats with 38/357 shotloads using Speer capsules. I'd load them with #8 shot as I was shooting trap at the time. It was very effective and patterning was good. Once I tried #12 shot with the same load and it was not good, just PO'd the rat which turned and cam...

I believe Charter Arms is producing a .44 Spl.

It's free although I think there is an enhanced version with better resolution, etc if you pay. Used it a lot when my kid was studying in Europe last year. Useful tool.