Welcome! This is a Military & Police revolver from 1899. These came in .38 Special (more commonly) or .32/20 Winchester. If you can find a .38 Special round and it fully seats in the cylinder, it is one of those. Literally millions of the same basic design have been produced, and the same basic model is still being made called the model 10.
__________________
Alan
SWCA LM 2023, SWHF 220
|