The letters RSG stamped on a ring means that the ring was preassembled. Any gems in the ring that is stamped RSG have not been certified.
50 Bucks...
The serial number should be stamped on the bottom of the receiver next to the forearm.
100 USD or so.
You can find it stamped under the forarm on the under side of the barrel and on the forarm its self
probably a manufacturer stamp
It’s the brand of the ring
The Riverside trade name was used by J. Stevens from 1915-mid 1940's. You MIGHT be able to get a precise date by contacting the Stevens historian. savagearms.com should have his contact information.
Marks stamped on a ring may tell you the manufacturer as well as the composition and metal quality.
"STERLING" stamped on a ring indicates that the ring is made of sterling silver, while letters stamped on the inside of a ring could represent the manufacturer's mark, the metal purity mark, or any personalization done to the ring. It is common for jewelry pieces to have these stamps for identification and quality assurance purposes.
I got one from e-gunparts.com, which is Numrich. They have schematics for many guns.
If it is a Side by Side like my Western Long Range Gun, pop off the forearm - mine is marked in three places: the wood of the forearm, the metal of the forearm, and on the action. My Model 37 has the serial number stamped on the front of the reciever, opposite the slide for the pump. It is in the area between the magazine tube and the barrell.