The RW above the serial number is a date code remington used to use.
First letter is the month:
BLACKPOWDERX- each letter is a month. Yours would be an R denoting November.
The 2nd letter is a year, W stands for 1929 in this case. So you have a model 12 manufactured in November of 1929.
Here is a link with more detail and a list of years:
http://www.wisnersinc.com/additional..._date_code.htm