The good thing is, that the targets are pretty big. And you don't have to hit it right in the center.
I bought one of the Crosman resetting squirrels. I guess it's pretty much regulation size, I think.
Not too hard to hit out to 40 yards. But after that I must be losing a lot of speed, because drop and wind start making it very difficult.
I heard of guys using 12 fpe guns. But that's a tough shot at 55 yards with a good breeze blowing.