Your Winchester model 1400 semi-auto shotgun is valued at between 140-220 dollars,depending on overall condition and a good bore.
Your Winchester model 1400 semi auto shotgun is gas operated.
How old and how much in value is a Winchester semi- auto 12 gauge shotgun model 1400 MK II serial number 483251
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.
Best to ask a gunsmith.
100-250 USD or so
I paid $200 for mine, although the tip was cut off the end.
A Winchester Model 140 12 gauge, semi automatic can be worth up to $150. The exact amount that the Winchester is worth depends on the condition of the gun.
The 1400 Mk II was made from 1968-1974
This is really a Winchester model 1400.
The Winchester model 1400 Mark II was only produced during the years 1968-1972.That is the time frame of your shotguns manufacture.
Check with numrich gin parts corp,or you could look for them at egunparts.com.