I live in lower michigan where we have to use a shotgun. I have a H&R Ultra Slug Deluxe and an inline muzzle loader. I think you would be fine with the 270. Heck, I think you could get away with a .243 if you were really worried about recoil. I think 200 yards and in would be pretty realistic distances and either caliber would work well for that. Either would also work well on coyote and varmints if you wanted.

I would do some checking, my guess would be the .500 S&W would be simular to most of the new slug loads. Might be a better way to go?

Paul