A easy one- if an American mfg. boxlock ejector gun for your 3" 12 heavy mag loads- the Burt Becker/AH Fox HE or Super Fox- the only thing I might add is rebounding hammers to the simple and strong as hell AH Fox action- If you want a European mfg. boxlock ejector to meet the same criteria- the Lindner Daly gets my vote- I won't discuss Over/Unders or Limey guns as they aren't "my bag"-- I have a older 12 2E Smith now with 32" Nitro tubes and 3" chambers- not a Longrange- and I use it with the Hevi-Shot Classic Doubles loads and it eats them up, spits them out and the Geese drop like Lead Zeppelins- The older Smiths on the longer R frame with the larger barrel lug into the receiver recess are great guns, what gave Smith the "bad rap", IMO, was the complicated and trouble-prone Hunter One Trigger--

"The field is the touchstone of the man"..