Brownig used to make a micro medalian citori in 20 Ga with 24" barrels....it was a real sweet gun for the "vertically challenged" shooter. I bought one for a lady friend of mine.....she loved it and still hunts with it.....there's nothing wrong with a 2 3/4" 20 Ga.....birds drop just fine with them.

You might also want to look at the Franchi Veloce in 20 or 28 ga....the stock may want to be shortened but the gun is superb.....