Serial number pre-fix letters in the rifle serial number on the receiver (not on the barrel) will get you to the nearest decade of production. If you need something more precise, call Remington.
Again, these are rifle serial numbers and have nothing to do with the barrel dating codes found on barrels just in front of the rifle receiver.
4,5,6,and 7 digit Model 700 serial numbered receivers-from 1962 to the early 1970's.
A prefix-began in the early 1970's
B prefix-began in the the late 1970's
C prefix-began in the late 80's
D prefix-began mid-late 90's - some recognized by ISS/J Lock firing pins
E prefix- ~2000/millenium (Embellished/engraved Model 700's/ISS/J Lock Firing Pins)
F prefix-began mid 2000's
G prefix-current/recent production
RR prefix - more recent production (largely CNC receivers) Some people including custom smiths who build off Rem 700 actions say these are truer actions than older ones. People who hate Remington for whatever reason will tell you that they are junk. I'll go with custom smiths who say these CNC produced actions need very little, if any at all, "blue printing" to make them shoot well.
All S/S receiver serial numbers have a prefix letter S
All Titanium receiver serial numbers have a prefix letter T
Rem Custom Shop Model 700 receiver serial numbers are sequenced w/ a Suffix Letter.
No short action Model 722 (1948) or 700 (1962) rifles existed in 1946 as AW stated. A Model 700 barrel code of RR most likely designates a November 1997 manufacture of a Model 700.
The two letter designation on the barrel in front of the receiver (not a serial number) will get you a rough year and month designation on the age of the Model 700 using the following code at this link. NOTE - Beginning with the first sentence, not everything stated here is totally accurate but the month and year date codes further down the page are good. Also notice what happened in 1999 with the barrel codes.
The text following the barrel code information is fairly good. Take time to read it all.
http://leeroysramblings.com/Gun%20Articles/remington_barrel_date_code.html