109K713 would be the serial number and = 1981.I own two S & W hand guns and would like to find out what there productions dates are.
1. A 357/38 mod 66-1 revolver with the following numbers.
109K713 with 215X6 below that.
2. A 41 mag model 57 with the following numbers
14X74 and A4 below that. .
The numbers for the model 57 are assembly numbers. Get the serial number from the underside on the grip frame. It will likely have a S or N prefix. If you have target grips you will need to remove them to see it.
Jim