I use a 20ga for duck quite a bit along with my 12ga. For an over and under there are some higher priced guns that come with extra set of barrels. Stoger makes an over and under combo that has 12 and 20ga barrels. One thing with stoger condor field combo has both barrels. One thing if you go and buy used with this gun, DO NOT get one made 2004 and before, they had allot of problems. My 20 and 12ga stogers are awesome guns and reliable.