This website is pretty accurate for rifles. The date code is on the barrel. Shotguns often do not have the barrel that it left the factory with, so the info isn't always right with shotguns. Would be rare for a rifle. Note that the same code is sometimes used more than once for years. But the 700 didn't exist prior to 1962, so if you see the same code for 1975 and 1946, you know it can't be 1946.
Also, they did not date stamp barrels 1999-2001.
http://remingtonsociety.com/rsa/questions/barrelcodes
ADL is Remingtons designation for blind magazines.
BDL is their designation for guns with a floorplate.
DBM is the designation for detachable box magazines.
No more, no less.
If the gun left the factory as ADL or BDL it could have been converted. I've seen people go in both directions with custom guns.
Over the years Remington has made dozens of configurations of both ADL and BDL. Not so many DBM's.
Many folks get hung up on many other details. MOST BDL's came with a certain set of features. Same with MOST ADL's, but not all. There were so many different variations of each that the method of unloading is the only real difference.
The SPS, CDL, LTR, Classic, Mountain Rifle, Sendero or any other gun ever made a floorplate is just a variation of the BDL. They even made a SS ADL version of the Mountain rifle for 2 or 3 years.