Researcher, I stand corrected about the incorrect use of the term 'grade'. I should have said solid rib 2& 9/16" 16ga marked 'skeet' on its frame. That gun had exhibition quality wood that matched in both the forearm and butt stock and it was clearly marked 2& 9/16ths" on the barrel. It had a 26" bbl. It wasn't a run of the mill gun by any stretch, but I don't know its history and it was well used, but not abused, when I acquired it. Perhaps it wasn't a model 12 skeet 'gun' in any normal context at all and came from the custom shop? I dunno. I do know it was a desirable gun. I saw & handled two dif .410 model 12's several years ago; their owner told me there were six made, all prototypes. He said that he had owned three, but I didn't see the third one and a forth was known to exist, but the other two were yet to be located. I'm NOT an expert on Winchesters, but did own the gun I mentioned, 35 years ago or so. I've also seen and shot solid rib model 42's factory marked 'TRAP', though I've never owned one of them personally.
With apologies for the thread drift & thanks for the times you've assisted me. This time too; its a large part of what keeps this board the best easily accessed source of accurate information.