What is the value of a Winchester model 1897 nickel plated riot or police shotgun serial number C567257.?

The value of your 1897 shotgun which was made in 1914,could only be determined if you supply a more descriptive explanation of your shotgun including marking found on the shotgun,its stock,barrel length,amount of original finish remaining on the wood and metal,if there is a heat shield over the forward end of the barrel etc.These shotguns can be worth quite a bit,and it may benefit you to have it appraised by a member of the Winchester collectors assoc.