9mm had me thinking German/European . Top view looks like wheat branches engraved rear of the ejection port.
Looks like not enough room for recoil spring assembly.
Manually cocked for each round??? No stamps to country of origin.
Maybe an underground/assassination type pistol from WWII???
No expert, just observations
Hellfire, Doom, Watch the hatred spin
Beyond the speed of sound---
Fire it up, Let the engines roll
It's time to burn it down