RE: What is a good duck gun?
Buy good shells for it. Kent Fasteel 1-/18 oz #2 loads at 1560 fps and let them get close,,, 30 yards or so.. If your buying a new gun,, most of them are 3" chambers now.
Those shellshave1/16 oz less shot that my 3" duck loads,, and I knock them dead at 35 yards.
speed kills with steel duck loads!
You could buy bismuth or tungsten matrix,, theyre costly but its like shooting lead.