Remington Firearms are dated by using a 2 or 3 LETTER code stamped on the barrels, not by a serial number. This is a link to the Remington Collector's website showing the letters and their location on the barrel. Good luck! https://www.remingtonsociety.org/manufacture-dates/
You have to hit it with a slede hammer until it breaks down then you've done it
Manufactured: 1913 The manufacture month and year of a Remington rifle can be determined from a letter and number code stamped near the back of the barrel on the right side. If your Model 12 is not marked 12A, 12B, 12C, 12CS, 12D, 12E, or 12F, it is a basic Model 12.
This would be a model 12CS made from 1909-1936, if it was made after 1921 it's date code to determine (month/year) is stamped on the barrel. The details for this can be found on the Remington Society of America (collectors site) http://www.remingtonsociety.com. This site also has a public forum available for more specific questions and answers. Given a serial number the date (year) of manufacture can always be determined. Value is determined by condition.
It was made in 1929, you didn't mention what caliber probably 22 rf so with a octagon barrel it's a 12C (if it is a .22 WRF / REM SPl) then a 12CS. The value is greatly dependent on condition in mint condition as high as 1,200 drops to 1/2 that price at 90% and then drops quickly from then on.
12cp + 12cs= 12cwg