Rory,
to the best of my knowledge and records, your listed #3 does not exist... I have never seen a prewar R or RS that had a three point buttstock but a two point forearm.
Also, the RS was not offered in 303 or 30-30. The R was cataloged in the 303 and several here own them. The R was not cataloged in 30-30 but a group of them was built at the factory on order for Spiegel guns.
I know that RSs were cataloged in the post war eras but I have yet to ever see a box, hang tag, or letter stating that a post war RS ever actually existed. If it did, you wer just paying extra to get a reciever sight but were getting no rear sight... The prewar RS included added sling studs, sling swivels, and a sling as well as the tang sight and a fold down rear sight. The Post War RS does not seeem like a very good deal from that stand point.
Long story short, I only see three transitions in the RS and have pretty tight data on what serial ranges the changes happen... first is the not fluted to fluted change, second would be the three point to two point checkering change, and three would be the change from the tang sight (Lyman windage adjustable) and rear fold down sight to the receiver (redfield 70LH) and rear sight blank.
