Very little, and possibly worth 10-years ina federal prison and a $250,000 fine if it is found to be any fractional bit less than 18-inches.
Winchester never made a Model 97 with an 18-inch barrel, so what you have is a non-factory cut-down gun. The shortest barrel length made by Winchester was 20-inches.
Receiver/barrel
Check the receiver and barrel
On the barrel.
barrel, tang, receiver
Check the receiver and barrel.
Check the receiver and barrel area.
Check the receiver and barrel
Check the receiver and barrel
Please include the model number of your Winchester shotgun to get a correct answer to your question along with the serial number.
on the bottom of the barrel and reciever.
Barrel and receiver are the most common place.
You have to provide. It will be on the receiver or barrel.