no. the serial # will normally be 5 digits.
The RemingtonModel 121 fieldmaster was introduce in 1936 and discontinued in 1954
Check date code on barrel - see related links
When was the serial? They all have serials. They were made from 1936-54 and have date code stamps on the barrel which can be looked up on the manufacture date link on the Remington Society of America.
June, 1941
All 121's are date code, see related links for the table/information for looking it up.
This serial number was produced between 1936 and 1954 out of a total of 199,891 Model 121s produced.
June, 1948
The model 121 was manufactured between 1967 and 1973. That's about as close as you are going to get. Update, Federal law required all firearms manufacturers to use serial numbers in 1968. If the Winchester 121 does not have serial numbers, if was manufactured in 1967.
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.
March 1940
Check the date code stamp in related links.