What you intend to shoot with your fowler makes a big difference in what gauge you choose. If you are going to hunt upland game, I would recommend 20 gauge or less. This would also be my choice if I intended to shoot round ball loads to any degree. If you are leaning towards doing a lot of waterfowling, I would go with a 12 gauge. Waterfowl just take a lot more shot to bring them down. That being said a 12 gauge shooting a round ball usually either falls way short of your target, or if you put enough extra powder in it to make it shoot the extra distance kicks the bejabber out of you.
My preference is the smaller gauges. My sons little trade gun will consistently shoot killer patterns, and break clay pigeons at 30 yards, and its a cylinder bore .410 made from an old cartridge barrel cut in half and repurposed for a miniature tradegun.
You really can’t find a much better gun kit than the fowler available from Jim Chambers in my opinion.
Hungry Horse
Hungry Horse