16 Gauge Shotguns
• You'll be an original because nobody hunts with them anymore
• Nearly impossible to find shells
• Manufacturers aren't making 16s anymore
It's been called "The Disappearing 16" for a reason – it is headed the way of the dinosaur thanks to the popularity of the 20 gauge.
There's very little a 16 can do that today's 20 cannot accomplish.
If you can still find the shells they will likely be more expensive than gold or in a very dusty box rammed to the back of very dusty shelf.
Besides just being an issue of comfort, the "what gauge?" question can't truly be answered without addressing shooting skill level.
Even the largest upland gamebird has a brain roughly the size of a pea. It hypothetically only takes one pellet straight to that bean in order to dispatch the bird. So, regardless whether you wield the pea shooting .410 or a 12 gauge bazooka, if you can connect lead to head the bird is dead.
There is no doubt that you can pack the most pellets in a 12 gauge shell. But, Annie Oakley didn't need more projectiles -- and neither do some hunters. The tradeoff for quantity of shot is normally the weight of the gun and recoil. A pound or two may not seem like much until you try hefting it around for 8 to 10 miles.
So, it's a balancing act. And once again, it comes down to what you are comfortable shooting and carrying. There are hunters who can consistently down roosters with a .410 and feel that anything else is overkill -- and for them that may be true. But, the 12 gauge is the most commonly fielded gun, period. In any given outdoor store you'll find the widest spectrum of 12 gauge shells, and it's likely that 2 out of every 3 hunters you come across in the upland field will be lugging 12s.
Effective and efficient dispatching of the bird is the most important issue, followed by whether or not you're able to lift your arms at the end of the day's hunt and then whether the bruising on your shoulder will allow you to hunt the following day.
Carry what you can shoot.