My uncle Pete was a big time, he went every year to Iron Mt to hunt, he used a 30/30 on deer and bear and a 12 gauge shotgun on squirrel and rabbits.
Very successful hunter, rarely bought a piece of meat at the grocery store.
"hmm I thought you used rifles with scopes not shotguns to hunt deer? I'm not a hunter, just a handgun carrier, but it seems to me a shotgun is more for use on birds and small game like squirrel & rabbits, not big game animals like deer. A 30/30 would be a better choice of a deer hunting gun."
Some states mandate shotguns only for deer hunting, hence "buckshot" or slugs. Their thinking was that a shotgun's limited range would make the hunt more "sporting" and the massive trauma from a slug or multiple buckshot hits would be a more humane death for the deer.
Personally I have found a well placed shot with my 30-06 is quick and quite humane.
Rifled slugs are the preferred ammo. Most muzzle loaders have similar ballistics to the modern shotgun/rifled slug, so there is a muzzle loader season there now.
Now I live in North Dakota, and use a .30-06 instead of a 12 gauge. (I did take my first whitetail in MD with a .410 long ago....I was 11 years old.)