I remember a lot of those H&R revolvers around in the 1960-70's. Very inexpensive revolvers, but were ok to plink with. I doubt if they have much value, unless is something very unusual.
GB had this thread listed:
Blue Book of gun values.
22/22mag convertible,Western style,double action, 5.5 or 7.5" barrel Mfg. from 1976 -1985. Prices as such 100% = $250 98%= 225, 95%=175 90%= 150 80%= 125 70%=100 60%= 90. You can also drop the value since your revolver is missing one of the original cylinders.
Info thanks to blue book, Bill Goforth, descriptions, Jim Hauff, pricing