Rabbits (Cottontails) are soft skinned & easy to kill. I always preferred # 5 or #6, not for their greater penetration but to simply not fill them with so many shot. Once when hunting with a 20 ga Ithaca Flues which had two inches cut from the barrels I inadvertently left a 7/8oz load of #9's in my vest pocket & loaded it in the right barrel., near cylinder. Shot a rabbit broadside at around 20-25 yds. As Jerry Clower would have said it was killed Graveyard Dead but made hamburger meat out of it, wasn't fit to eat was so full of blood shot meat.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra