I appreciate the effort each of you has gone to to try to solve my oddball problem. I will be out of the country for the next three weeks and will be unable to see any more replies. When I come back I hope to find that some kind soul has identified a particular model 12 gauge and a particular chambering to go with it. Not too expensive, please. It is one thing to abandon a $1500 gun and another to abandon a $15000 one.
Cal
in the original question, you stated the late 19th early 20th century, a D grade Parker,(a common choice for "well to do" but not wealthy gentleman) was the lower "custom" grade and cost $100 at that time. Not a petty sum in those days when the common man's wages were measured in cents, but far from $1500 or $15,000
A common D grade Parker would be a 1 1/2 frame 12 with 30 inch barrels, it would be nicely engeaved and chambered for the then standard shorter paper cartridge. If you want to decribe the looks of a Parker, go to the Parker Collecter's board
http://parkerguns.org/index.html and click on the Parker Grades link on the left.
but still, to be believable to shooters- location and sport will affect the choice. When I was active in 18th century reenacting there were always guys who really wanted to carry something way above what their chosen peronna would have used. The inevitable explaination was something like- oh it was a gift from an officer for saving his life or some such whimsy. If you reay want to make it believable - the choice needs to fit the person.
for the general reader - heck say anything, My wife and kids always say who cares when I mention that a movie's time period predates the weapons shown.