Looking at the four pairs of guns in D's attachment, you see many subtle and not so subtle differences in each pair. I could look at those guns for a long time.

The other 28 I had in my hand was in 1987. A 26" full choke gun with 20% blue. The price was $1300. I thought about it and went back to the dealer only to find out that it had disappeared.

Just be aware that there are more 28 gauge model 12s floating around than Winchester ever made.

Does someone reproduce them?

Quite a few 28s have been converted from 16 and 20 ga guns. There was a run of Japanese
made reproductions. I personally have never seen a plain barrel gun that has been converted. I have seen solid ribbed and vent ribbed conversions. If you know where to look, a conversion can be identified.

Exactly... Frank stated that very well. When looking for a 28 gauge Model 12 you really need to know what to look for in an original gun. There are many humped up 28 gauge Model 12s our there