Breaker,
The Mannlicher style bolt handle was standard on the Model 21/22 Series rifles. At the very end of production (1956?) the ZG-47 was in production also and some of the very last 21/22 rifles were fitted with either the round ZG-47 bolt knob (with dimple) or the ZG rotating safety or both. I have a model 22 from 1956 that has the ZG-47 trigger and bolt knob but the standard safety.

John