Frase, your smooth bore is not very likely to give you a good pattern for skeet as it has no choke. With small shot and bird shot, you have a shot column that can benefit by the shaping of some choke.

Buckshot, in those areas that allow it to be legal, is very effective on medium size game. I have heard deer hunters say that you need to pattern your shotgun & try to get 3 pellets minimum or so in your target of the 9, 12, or 15 that it has loaded in it. Otherwise, my experience with buckshot is in soldiering and I will skip that in this forum.

Good hunting.