FWIW, the local expert on M12 28s told me that all of these guns had a 20 gauge barrel band (& he's personally owned quite a few). He also confirmed that you can't really fake the swaged and crimped magazine tube.
He is right- they are the same size- later on in production, a "running change" perhaps, they were stamped 28, but he is correct as to the same dimensions- Sounds like you have taken all the right steps here Lloyd--great indeed that a double gun forum could contain as many experts and collectors of the great M12- not named the Perfect Repeater for naught. I am going to a small area gun show the last week-end of this month, and the word has it that a nice collection of mainly pre-WW2 Model 12's will be offered for sale- we shall see- can always fine room for a few more in the 32 gun Browning safe-
