I kill squirrels fairly reliably out to 30-35yd with a Chiappa .22/.410 combination.
I load Winchester HS 3" hulls with #6 plated shot and H-110 for this purpose. I think the plated shot is extremely important to help keep the shot round and prevent fliers, which IMO are an even bigger problem with the 3" "magnums".
I really like #4 for squirrels in the larger gauges, but with the .410 I think it makes the patterns too sparse at longer ranges, hence the #6. (Again, I've just shot printer paper with a scale picture of a squirrel on it, not proper patterning boards. :P )
The gun shoots very tightly, which I appreciate (and is surprisingly well regulated for a cheap gun). I don't have a proper bore gauge to measure the bore and choke with, but it puts most all the shot into about 10" at 25yd (this just shooting at an 8.5x11 sheet of paper to check the regulation when I bought it). Shoots like a turkey choke.
Anyway, that load out of that gun really smacks the snot out of the squirrels, even at the tops of the tallest trees. I am rather fond of that little gun, even though it's pretty crappy.
I don't try to shoot flying animals with it, though. I'm not good enough to want to shoot a .410 at anything airborne other than clays.
