The ejector style on that piece is fairly common among European revolvers. You usually unscrew the center rod projecting from the cylinder pin about a quarter turn to unlock it, then withdraw it toward the muzzle and pivot it to the right (the right side as you hold the pistol normally). Then it acts just like the ejector on a single action Colt, pushing the empties out individually.
Do you know the caliber of that little bulldog-style revolver?
This YouTube video by Henrique Sjeffers of Belgian revolvers shows a very similar gun
They were everywhere: pawn shops, flea markets, and even a few gun shops. He probably bought it, like many of the "war trophy" rifles.Now the only mystery is how in the world did my Dad get his hands on a Belgian made pistol?
Quite possibly 32 S&W or 32 S&W Long. If it is old enough, it might be chambered for 320 Revolver or 32 Rimfire. Check the bore diameter, chamber length, and where the firing pin strikes, then get a copy of Cartridges Of The World and figure it out.ID of the cylinders is aprrox 7.5mm