Remington factory barrels are "indexed", i.e. they are produced so that they will screw into any Remington receiver for the same kind of rifle and the sights will line up on top, the barrel markings will be in the right spot, and headspace will be pretty close. When they are produced at the factory, they are hammer-forged (complete with chamber), ground to profile, polished if needed, then roll marked. In production, they grab a barrel, screw it into a receiver, torque it in place.
Winchester used to do the same with their barrels. Springfield Armory used to turn out 1903 Springfield barrels chambered and with the front sight in place, all the armory guys had to do was line up the witness marks. It is not an uncommon thing. An unmodified Remington 700 barrel removed from a Remington 700 rifle will screw into another Remington 700 action and be very, very close. Still check the headspace, but it will be close.
Now, if some gunsmith cut the shoulder off of the barrel shank so he could unscrew the barrel, that is another story.