Severly limiting range eh?Unless you are an expert and don't mind severely limiting your range and number of shots. (You already admitted that your are not, or at least are not experienced!) Otherwise figure on losing lots of wounded birds because you didn't!
20ga, Winchester Double-X magnum, 3in, 1 1/4oz, 50 yards out of F-choke.
http://www.axcessmypics.com/photos/phot ... c4cbc1.jpg
Maybe it's just me, but it would be rather hard for a rooster to survive that pattern.
As to the original topic, shoot a good shell, and you really don't lose much if anything to the 12.