9mmMike:
For a time Remington put the "matted" groove on all shotguns, including the Express. This too was deleted to save costs, and my recent 870 Police has a smooth groove also. Apparently, this is now a Wingmaster-only feature. In truth, because of the parkerized and rough black finishes used on the non-Wingmaster guns, the matting really isn't necessary.
A visit to the Remington web site, indicates that they may no longer be using the "special purpose" designation.
In past years you could buy a standard gun like the Deer Gun in a Wingmaster, with gloss blue and your choice of gloss or satin stock finish, OR a Wingmaster Special Purpose with a parkerized finish and dull wood.
The Special Purpose was made in a variety of guns for a variety of hunting purposes, primarily duck and goose, or deer hunting.
I'd suspect your gun is simply missing the ejector spring, as it's unlikely it would have made it out of the factory without one.
What is possible, is somebody needed/wanted to replace the ejector for some reason, only to find out that the Remington's require a special tool to re-rivet the double-headed rivets. They would have, of course, found this out AFTER removing the old one.
Unable to fix it, they passed it on. This is what usually happens to guns that somebody has had a "misadventure" with.