Cow horns curve to the right or left. Depends on the side of the cow it was on. If you wear your horn on the right then you need a right handed horn because the natural curve of the horn will curve around your body making it more convenient and easier to carry. Same goes for the left side. And just because you are right handed doesn't mean you will wear it on the right side. Some guys prefer the opposite side. So that question isn't are you right or left handed. It is will you wear the horn on the right or left.
In the large horn, depends on how much you plan to shoot. A large horn holds a tremendous amount of powder. I don't know that many guys would run out from a large horn in a few range sessions. I prefer small and medium horns so it boils down to how much powder you want to carry.
