You really need to know a couple things first. Coil or band spring for the trigger? Direction of owls on grips? Patent dates? Barrel rib markings? Letter prefix on serial number.
I am no expert, but have learned from the experts here, that without this info, its impossible to tell, and with it, pretty much assured to know.
I am no expert, but have learned from the experts here, that without this info, its impossible to tell, and with it, pretty much assured to know.