I think this is correct, but H&R info is a bit hard to find.
The first sideswing H&R was the Model 929 Sidekick, a neat term based on the side swing cylinder. There were two variations, the second had a transfer bar.
The 930 was the same except for having a nickel finish; there were also two variations, the second with the transfer bar. The 930 was not available with a 6" barrel.
The 939 Ultra Sidekick, was similar, but with adjustable sights and a vent rib. Again, a second variation had a transfer bar. The 6" barrel was flat sided. I believe that the 6" barrels were marked "Ultra Sidekick".
The 940 was also called the Ultra Sidekick, and was the same as the 939 except for having a round heavy barrel. Again, the two variations, with and without the transfer bar.
The 949 "Forty Niner" and 950 (nickel plated) were the same gun internally, but with a SAA style grip and a fake ejector rod that was pulled forward to open the cylinder. They had fake stag grips, and were made to take advantage of the 1960's "cowboy craze".
Jim