The Walther Olympia is .22LR Target/Competition pistol developed in the early 20s meant for serious plinkers and competition shooters, it's basically a simple blowback pistol that has an internal hammer fixed barrel and decent enough sights. There are models out there that has weights that was able to balance the weapon for really serious shooters.
Most of the accessible models are now made by Norinco, which has somewhat dubious reputation but who's gonna complain about a dinky .22LR, right? Accept muzzle devices and pistol stock and has its own 10 round magazine.
Model from Ovidiu with support from Riceler, thank you!