Winchester made the 2.50in chamber in their shotguns up until 1927.In 1928 the change over was made to the 2.75 in.chamber on their shotguns.
The winchester model 275 was produced by winchester from 1963-1975.
It is .22 caliber- gauge refers to shotguns. In very good condition, prices run about $225-$275.
If your shotgun is new in the box(unfired) then between 275-310 dollars.
Between 100-275 dollars depending on overall condition and a good bore.
Without a detailed description of your shotgun,I can only say that in general value this will range from 275-475 dollars.
If your shotgun has good wood and blueing,then the Winchester model 12 shotgun will bring between 275-450 dollars on today,s market.The gauge of the shotgun helps also with the 12 gauge being the most prevalant,and the 16 gauge and 20 gauge being produced a lot less,hence more value.
375 dollars
Your Winchester model 12 shotgun with a original finish ranging between 60%-90%,will be valued between 275-475 dollars.
Your Winchester model 1912 pump action shotgun,which was produced in 1917,will range in price from 250-450 dollars based on your shotgun having between 60%-90% of its original finish remaining and in 12 gauge.If you have a 16 gauge model then 275-475 dollars,if you have a twenty gauge model then 450-675 dollars.
With the serial number that you have given,your Winchester model 1912 pump action shotgun was made in the year 1961.If it is in 12 gauge then the shotgun has a value of between 250-325 dollars for a specimen showing between 60%-80% of its original finish,if in 16 gauge then 275-375 dollars,if in 20 gauge then between 450-575 dollars.
With the serial number that you have provided,your Winchester model 1912 pump action shotgun was made in the year 1953.If your shotgun shows between 60%-80%of its original finish and is chambered in 12 gauge then the value will be between 250-325 dollars,if it is in 16 gauge then 275-375 dollars.
Its unfortunate that Winchester did not keep records of the production by year of the model 275.I can say that these .22cal rifles were made from 1963-1973.