That's a Model 929. The grips are what they called "STAG" colored. The ejector rod with the steel sleeve around it dates it to right around 1957. The serial number, stamped on the bottom of the butt strap, should start with the letter S, T or U (let me know what it is and we can determine the year). The crane lock up on that one should be a spring loaded plunger that comes down from the top of the frame and there should be a small screw up there. The firing pin should be attached to the nose of the hammer (which is jeweled or machine turned, only done for a few years in the late '50's and early '60's - too costly).
The Model 929 was H&R's FIRST swing out cylinder revolver, along with the Model 930 (nickel plated version), the Model 732 (.32 S&WL) and the nickel plated 733, also in .32S&WL. This model was also the first swing out cylinder revolver made by any of the "Blue Collar" gun manufacturers. It was very well accepted in the market and lasted in production, in two variations (second var. had a transfer bar safety system and frame mounted firing pin), until H&R went out of business in 1986. Model 929 was available in 2 1/2", 4" and 6" barrel lengths
It is a strong gun, with a coil wound main spring, and is capable of handling any .22 lr factory round made today (assuming it is in safe condition to fire.) I hope you find this info interesting and thanks for the opportunity to share some of my info.