The circled W without the other US marks is almost certainly commercial. Following WW1 Winchester sold the Model 97 shotguns with the hanguard sleeve/bayonet stud to police departments and there is good reason to believe that they furnished these non-US marked bayonets with them. I have been told that there are Winchester ads from the 1920s that show the shotguns and indicated that they were furnished with bayonets.

They are definitely scarcer than the US marked versions, but have a somewhat smaller collector following since they cannot be proven to be US military issue.