I've used the Hevi-Shot Dead Coyote 3" loads, and they definately do a good job.

Also look for a heavy load of Copper plated 1 5/8 ounce BBs. They work very well as well.

I wouldn't use the OO buck, 4 buck hits the the hammer of Thor.

Just make sure to spend a little time experimenting with different chokes pattern testing.