The Remington Model 12 was made from 1909 to 1936. It's year can be determined by it's serial number and those from 1921 are date (code) stamped and the month and year can be determined here: http://remingtonsociety.com/rsa/questions/barrelcodes
Made from 1909 - 1936, with a serial no I can tell you a year, from 1921 on there is a barrel code with month/year. Check Remington Society of America...
The Remington Model 9 is a single shot shotgun manufactured during the period of 1902-1910. According to M. J. Kantor who worked for Remington Arms Service Division, in a letter dated December 23,...