Can anyone tell me where the serial number on a Winchester model 131 is located? I looked everywhere and can't find one. This gun was manufactured between 1967 and 1973 with only 16,371 produced. Could this be a case of the gun being manufactured before the NFA was enacted and thus serial numbers were not required? Any info would be helpful.

not required b4 68 so it must be an early one, altho there were ser. nos. on other .22s before 60, remington for example.

Thanks

FWIW I've got an old Remington Pump that doesn't have a SN and also an old Steven's Crackshot that doesn't have a SN. If you can't find it easily, it probably doesn't exist. It's not that uncommon.