I do not believe that the serial numbers for the Winchester model 140 ranger,semi-auto shotgun are in the public domain.I can say that the Winchester model 1400 was made from 1964-1981,and this was the higher priced version of the model 140 ranger shotgun.
Your Winchester ranger model 140 was made from 1967-1973.Winchester did not keep serial number records of this model of shotgun.
Blue Book of Gun Values
Your Winchester model 1400 semi-auto shotgun is valued at between 140-220 dollars,depending on overall condition and a good bore.
The Winchester 140 12 gauge has a choke barrel at 28". This is the same choke size as the 20 gauge model.
value Winchester 140
100-300 USD
100-300 USD
Between 140-200 dollars for a shotgun having between 60%-90% of its original finish remaining.
you cannot increase the capacity of a Winchester 140, 1400 or 1500 because the gas piston is in the end of the magazine tube and must line up with the ports in the barrel
A Winchester model 1200 field grade shotgun will be between 90-150 dollars for a plain barrel model,100-165 for a vent rib barrel model,and between 140-200 dollars for a shotgun with the Win choke present.
I just paid $250.00 for one at Blythes gun store in griffith indiana