I use a pardner pump in 12 guage. I love it have killed several turkeys with it. Only chambers 3" mags but thats ok for me. I have a .640 hastings choke in it and it is a turkey killer. Good gun for the price. Don't know about the 20 guage, my wife hunts with a remington 1100 20 guage for youth and it is crazy light. But it will through a pattern very well for 2 3/4" shells.