No.As a matter of fact I have no records of Winchester ever making a model 6!Could you be thinking of the Winchester model of 1906 .22cal.rifle?
Winchester produced the lever-action Nickel Plated A Special model from 1901 until 1920. This model was part of the Winchester 1892 series and was known for its distinctive nickel plating, which was a special order option. Overall, the production spanned approximately 19 years.
while this is possible,I have no records indicationg this.Winchester made the model 1400MKII only from 1968-1972.It could have been nickeled at some point in time for Marine use(over water/salt water) or just for looks.
The value of a gun is based on exact make, model and condition. Those guns were not originally nickel plated, and will have lost most of their collector's value. You would need an in person exam of the pistol for an accurate answer.
To make them pretty and to resist corrosion.
It probably did not leave the factory with that finish. I would guess that the serial number is unreadable because the gun was polished too aggressively by whoever added the nickel plating. Without the serial number, a Winchester expert may be able to approximate the manufacture date by examining the gun, but the exact year cannot be determined.
Not factory
Winchester did not make a Model 30
Winchester did not make a model 81.
Winchester did not make a Model 1882.
Winchester did not make a model 96 shotgun,they did make a model 97 shotgun however.
Only the value of the metals used to make it.
Winchester did a lot of custom work for customers they considered "special", but unless you've got some sort of paperwork from Winchester, you're going to have a hard time proving it was done at the factory. As engraving is done by hand, and one piece at a time, even if the pattern matches, if you or Winchester doesn't have some sort of documentation, the work will be in question.