With all due respect, Texan, you can quietly walk up on a sitting rabbit and get with a short throw with a hood sized stick and kill them. Certainly, you only need a .22 pistol to shoot them. Why would you wnat to use buckshot on rabbits. Even those Texas rabbits will have to work hard to get to 5 lbs. on the hoof. Some people jump them and then try to shoot them with a .22 rifle. I would think buckshot would tear them up, even the small .24 cal. variety. Are you just shooting them as a nuisance, or were you planning to eat them? A 28 ga. is a fairly small bore gun, as you well know. Assuming you are going to shoot rabbits at 75 feet or less( 25 yds,) I would think 6-9 pellets would be enough. As has already been suggested, you have to see how your gun patterns them. so you have some idea of the effective range of the shot load in your gun. I fiddled around with a .410, which is much smaller, many years ago, but I have not had access to a 28 ga. gun to do this kind of work-up.