The furniture does look like it could be Russian.
The longer .22LR magazine you have is a harder to find variant. Externally it uses the stamping of a Romanian 5.56mm magazine.
It has been a while since I fired mine, but I had decent results with CCI Blazer.
Mine does not like hollow point ammo, so I seek out round nose lead.
I recently obtained 40 grain Norma Tac-22 to try but haven't had time for shooting lately.
If yours has any issues Black Dog Machine has offered some fire control parts and magazines, though part availability has been sporadic.