The BRNO M21/22 smallring actions are pure commercial develeopments, though the Czech had a consequent line in producing the smallring actions for military purposes.

Peruvian 1932 (identical to VZ33 except the typical Peruvian charger hump). BTW the Safety in this picture is from a postwar M21.

Wartime (1941) commercial 21

The wartime productions had a much better bottom metal.Solid steel box . The double set trigger mechanism identical to the later production times.Little different shaping ( rounded) of the trigger bow guard.

Not the cheap stamped and welded magazinze boxes found on the postwar production.

Sorry for my butchering the BRNO parts.