When I was Hunting in the South West, it usually involved wearing very thin clothing. Even in the winter, a light field jacket was the only required, at least in most of the hunting that I did. An Army field jacket was about the heaviest coat that I ever wore.
The 12ga with 3" mag buck shot has the recoil of a 375 H&H to a 416 Rigby...nothing to sneeze at. 3" buckshot loads have a very fast snap to the recoil, not a mild push.
Shooting very heavy recoiling guns leads may leade to a flinch in your rifle shooting, if you shoot the heavy buckshot loads in light clothing. Shooting Pump guns with heavy duck loads never bothered me due to the fact that I had on heavy clothing. The recoil of the Ithaca 10ga is not bad either which is more of a long push in felt recoil.
Like I said, the guy that shoots very little will have a different opinion compared to a guy that shoots a lot. A guy really has to examine his needs he has for each particular type of game he is hunting. If you want to use the shotgun for coyote hunting, then you may enjoy a 24" barrel or shorter. While for dove hunting, a guy may want a lighter gauge, and for duck hunting yet another type of shotgun.
When we were hunting yotes, we did not carry the shotguns very far. We would usually park the truck and walk 300 or so yards away and make a stand. We also carried the shotgun in a scabbord on a horse or mule. Coyote populations were very high in Mexico and in secluded areas in Az that were only approachable by horse back. If you could hunt on the leading edge of a low pressure front, you would shoot a lot of Buckshot. It has been my experience that you shoot about twice as much buckshot as rifle ammo.
I have never had any problem with my 1100 3" Mag. I was taught to wipe off the magazine tube each and every time I hunt with it when the gun has been fired. I have shot over 1000 rounds of Buckshot through this particular 1100 without problems, but I do clean it when it has been shot.
Weight was not ever a problem, even with the Ithaca Auto Mag. The Swing on the Ithaca 10ga was a problem however.
I can not stress enough the proper fit on a shotgun if/when you intend to shoot a lot. I had an Ithaca over and under 12ga that it was almost impossible to miss with, but the shotgun gave me a black eye. Any light pump shotgun would give me a bright red spot on my cheek from the gun slapping my face under heavy recoil. The Remington 870 and 1100 shoot about 8" low for me at 40 yards due to stock fit.
The Beretta 390, Browning BPS, and the Benelli SBE fit me
the best.
The poster wanted various recomendations as to a shotgun. If I had to pick just one shotgun in an auto, then it would be a Beretta 390 or 391. If a fellow were to be insistant on a pump, then I would pick a Browning BPS due to my fit.
There were several guns mentioned that I have never tried, it is very interesting to hear those comments.