yes 20ga is plenty big enough. Mine is a 20ga,26"fullchoke, my wife has a 28ga,mod.choke barrel. She got her turkey last year on her first hunt, 20yrd shot with winchester 1oz.#6 shot,droped it dead right there. I started with a 12ga.,then went to a 20ga. three years ago and got three Turkeys between 20-30 yrds. Just know your didtance and go for it !