thanks for your reply....
i did more research and talked to a local gunsmith.... best options i could come up with was to cut the barrel and install choke tubes....
called my friend, turned out it was a 16 guage....
he said don't worry, he usually uses his 20 guage with modified choke with a 26 inch barrel for doves.... he is about 75 years old, and i think every thing is fine with him as it is....
i did learn that winchester model 12 barrels are not commonly available, which is interesting, because i have several old 12 guage model 12's (retired, but serviceable).....