I just acquired a Model 10, 4 screw, unfortunately no box or papers. According to my SCSW the SN- C 4657..- puts it around late 1960. On the other hand, SCSW also says that the dash 1 began in 1959. Which is more reliable in determining when a Smith was made- SN or dash? I'd appreciate any help you can give.
The closest one on my list is about 6,000 lower, and shipped in 10/59. So yours would most likely have shipped early in 1960. Here is the list of changes and dates:
10-1 (1959): heavy barrel
10-2 (1961): change extractor rod thread for standard barrel
10-3 (1961): change extractor rod thread for heavy barrel, change front sight width from 1/10" to 1/8"
10-4 (1962): eliminate trigger-guard screw on standard barrel frame
10-5 (1962): change sight width from 1/10" to 1/8" for standard barrel
10-6 (1962): eliminate trigger-guard screw on heavy-barrel frame
10-7 (1977): change gas ring from yoke to cylinder for standard barrel
10-8 (1977): change gas ring from yoke to cylinder for heavy barrel
10-9 (1988): new yoke retention system, radius stud package, floating hand hammer nose bushing for standard barrel
10-10 (1988): new yoke retention system, radius stud package, floating hand hammer nose bushing for heavy barrel
10-11 (1997): MIM hammer/trigger + floating firing pin for standard barrel
10-12 (1997): MIM hammer/trigger + floating firing pin for heavy barrel
10-13 (2002): limited production 1899 commemorative edition
10-14 (2002): internal lock