Made from 1964-68; 50-250 USD
The number 1400 refers to the Model number of your Winchester shotgun.
The Winchester model 1400 shotgun was made by Winchester from 1964-1981.
Your Winchester model 1400 semi auto shotgun is gas operated.
Your Winchester model 1400 semi-auto shotgun is valued at between 140-220 dollars,depending on overall condition and a good bore.
How old and how much in value is a Winchester semi- auto 12 gauge shotgun model 1400 MK II serial number 483251
You don't specify a time frame.
Your Winchester model 1400 MK2 was made between the years 1969-1972.These were the only years that Winchester stamped there model 1400 with the MK2.
The Winchester Mark IV 1400 shotgun is relatively new on the market, and there are a lot of them in circulation. So the value is not excellent. Typically, this gun is sold online for around 150 dollars.
You should contact Winchester directly and go to customer service.They should be able to identify when your Model 1400 shotgun was made.
I can say that Winchester made the model 1400 shotgun from 1964-1981.But they did not record the serial numbers by year of production.