Matching pellet size to the situation(game) is more important with the .410, IMO. A poster in another thread mentioned that a single pellet in the vitals of a rabbit will kill reliably. I wouldn't argue that at all, but would say that a single #6 will do a lot more than a single #8, or even #7 1/2. I would never hunt rabs with anything smaller than #6s. You just need a bigger pellet to penetrate to the vitals. Downside to that is, less pellets per load, and that gets critical with the .410. I killed lots of rabbits as a kid with my Tenite stocked .410 and #6s, most of them sitting. Didn't have a rabbit dog.
SRH