Originally Posted by turnerriver

507 is the model number, it doesn't provide size information. My guess would be a medium frame DA revolver. The holster was made prior to WW II
and is an unusual model not often seen in.basketweave finish.
Look on the back with a strong light and you might find inked or etched information such as OP, AS or MP which would indicate Official Police, Army Special or Military & Police. It looks like a 6" barrel. You can feel where the cylinder ends inside the holster and measure for the barrel size. It is a very fine unusual Heiser
Regards,
turnerriver