Hi There,
Your revolver appears to be a .38 DA 4th Model. These were man-
ufactured from 1895 to 1909. The serial number range for this
model is 322701 to 539000. From your serial number (397856),
it was manufactured after the cut-off for Anitques (revolvers
made before serial number 382022 are considered Antiques).
I cannot be more specific about the date.
Cheers!
Webb