Some years ago, Remington made a series of "budget model" rifles and shotguns under the "Sportsman" name.
These were simply the standard rifle or shotgun with a lesser grade blue job and usually hardwood stocks.
The Sportsman pump gun was the Remington 870 in the budget version. The gun is nothing more than a standard 870 and all accessories, parts, and barrels will fit.
When Remington brought out the Express line, they discontinued the Sportsman.