Answer:
The Mossberg Rifle 45A alone is currently (2009) valued at around $200 or a bit more in very good to excellent condition, however, the "S" prefix denotes that it was sold with a scope. The No. 7 Mossberg scope and bases currently run around $200.00 - 350.00 or more depending on model and condition.
A history of Mossberg has been written and is available on Amazon
Think you have a New haven 250K. If so, it is the same as the Mossberg 152K, made from 1950-1957.
1888 at the New Haven, Connecticut, factory.
The Mossberg plant moved from New Haven to North Haven about 1962 when the Interstate (91?) came through the old plant.
Mossberg
The Mossberg and Sons Model 146B was manufactured in 1954-1958.
mossberg
One can find a clip for a 22 caliber New Haven Mossberg rifle through local gun retailers. These pieces can also be found through gun classifieds and gun manufacturers.
O.F. Mossberg, New Haven CT.
I belive it was mossberg? DEFINITELY!
My research indicates that this rifle was a Mossberg Mod. 46 which was manufactured in the late 1930's and early 40's
Most of the early work was done in New Haven, Connecticut