9 shot, .22 cal, model 929 - -
I bought a new H&R in a gun shop in the 50's that match that description.
lots of info on it in an article in Guns and Ammo HERE.
My dad bought a 939 at the same time.
He only had one arm, and the 939 had a cylinder release button behind the hammer, so it was really easy to open it one handed -
Looks like they made it from 1956 to 1986, and by checking your piece against the various changes described in the article, you can pin it down pretty closely.