Great input, guys. Don't know why I hadn't thought of a 10/22-we have a lot of fun with my BIL's up the farm. For some reason I'd been thinking of a Remington, but I think the Ruger or Savage would be a better way to go.
KUOA, I'm probably less than "average", but don't think I'd have too much trouble mounting a scope! That's one project I've never done, as most of my experience has been with shotguns for upland game.
TripleR, thanks for the video link.
I've thought about just bringing out one of my shotguns, but some of the shots would be a little long, and I think I'd have a better chance with a rifle. Besides, I need a new toy!
And the point about ricocheting off the water is well taken. I'm always aware of the possibiliy because one of my friends got shot in the arm by his brother when they were on opposite sides of a pond shooting at frogs. Thankfully it wasn't worse-the bullet went cleanly through his shirt and arm. They went home, cleaned the wound with hydrogen peroxide, threw the shirt away and never told their folks!