Pilot if I am correct the cylinder latch, and crane are on the left side of the revolver. If it is a Colt type the latch releases by being moved rearward. If not then it would be like the Smith & Wesson forward push type.
Actually, its neither. The H&R Model 939 has no cylinder latch per se but rather one simply pulls forward on the ejector rod to free the cylinder so that it can be swung out the left side of the frame like most other DA revolvers. I've seen several other older DA .22 revolvers of that design including the High Standard Sentinel series. Such a design probably wouldn't lock securely enough for a cartridge with much more power, but for a .22 it's plenty strong enough.
Smith, and Wesson, and Me. -H. Callahan
Well waddaya know, one buwwet weft! -E. Fudd
All bad precedents begin as justifiable measures. -J. Caesar