You can use a 20 ga., just have a full choke of some kind on it. BUT if you really get into it, and it'shard not to,then eventually you're going to want the best gun you can buy. If you want one call, buy a nice slate, they're the most versatile and easy to use. Also buy a few different strikers, they'll each make a distinctly different sound on a single slate. Practice calling as much as you can, but know that the most important tool is patience.