The RemingtonModel 121 fieldmaster was introduce in 1936 and discontinued in 1954
Check date code on barrel - see related links
no. the serial # will normally be 5 digits.
All 121's are date code, see related links for the table/information for looking it up.
June, 1948
1949 - there is a date code on the barrel for month/year details on the Remington Society of Amerca here: http://remingtonsociety.com/rsa/questions/barrelcodes
Winchester didn't make it, Remington did. Worth 222-350 depending on condition and lust level of buyer
Manufactured: 1947, value dependent on condition. I bought a model 121 fieldmaster brand new in 1954 and they were supposed to be the first hammerless pump . I do not know what year they originated but , now you know it was at least in 1954 or before . Wish I could pinpoint it better for you but you now have a jumping in point.
1946, it will be date code (month/year - letters) on the left side of the barrel. You can look this up under the manufactured date on the Remington Society of America site.
This serial number was produced between 1936 and 1954 out of a total of 199,891 Model 121s produced.
June, 1941
March 1940