I have a 22 falling block that is strange, I have worked in the gun business for 30 plus years and collected single shot 22's for that long too. This one is a Hopkins and Allen Junior model 922 but is actually a model 2922 becuse of the checkerd stock. 
If you look at Jim Perkins book on American Boys Rifles it's on page 122. This one is stamped H.S.B.co. thats Hibbard,Spencer & bartlett. They were a large Hardware compnay. The roll engraved stamp on the side says RE-VO-NOC, I know this much, that revonac is Coniver spelled backwards, this Coniver was the best sales person for the hardware company and they named a line of goods after him spelling his name backwords.

This gun is threded at the end. The BBl. is a larger Dia. than normal, my guess is it to put he thraeds on the end. Top of the Bbl.it has the word Noisless roll engraved in it.............I have got in touch with the H.S.B hardware collectors club, they have no clue, it dosen't show up any of ther catalogs. I believe it was a prototype, does anyone have any information about it ?

Dave McKee