Hawkman-, first things first--Go Hawks! A belated welcome to the 'Fire.
The 20 with an oz of shot 5's or 6's is just fine. Those that say not don't know.
Back in '69 a friend and I took 198 pheasants legally that fall and winter in NW Iowa because we had great snow, Government Acres (now CRP), and we cut way too many college classes. I remember the numbers because the hunting was so good we started keeping track, and I actually did a bio research paper on the stomach contents of my birds.
My point is I had a inexpensive Stevens 20 SxS and shot all those birds that year with it and many more in other years. Now, I shoot a bit of an upgrade--a Beretta 471 Golden Hawk 20 SxS--and it's still knocking them down and out.
There is perhaps something to going 12 late season for birds that flush wild and or in wind but if you have a twenty on a true twenty frame it sure carries nicer than a 12 and perhaps you pass up a few of those more challenging shots.
