if you are trying to shoot clays with a rifle then you really are making life difficult for yourself
Only kidding, clays are shot with a shotgun - rifles are the type of things you see snipers use, a shotgun cartridge is filled with tons of little pellets which spread over a wide range, thus making it easier to hit a small target (theoretically), whereas a rifle is a single bullet.
Just so you don't get confused when you go.
I have shot clays a few times but struggle as I shoot off my left shoulder which is my badly injured shoulder so it hurts like hell, chances are they will give you a nice light 20 bore which won't be heavy to lift or won't have a bad kick (the recoil bit).
Hope you have fun, and take your camera