Remington Society of America - questions/barrelcodes
For the first letter in the serial number of a Rem 700:
Letter A can be 1980 or 2006
Letter B can be 1981 or 2007
The Rem 700 didn't exist in 1954 or 1955.
Note that the letters are not necessarily in the "normal" alphabetic sequence. There are additional letters for the month of manufacture.