Is this a Miroku-made gun or an original Winchester? If the former it works just like your Browning, which is also a Miroku product, except for the rimfire ignition. Can't help with the production #s, but I know they have made "batches" of these rimfires over the years and they were introduced well after the centerfire versions. 1980s? They still make 'em; my .22WRM was made in 2015 (or at least that's when I bought it new).
The original Winchester rimfires were made from 1885 to 1920.
