no it is not classified as a pistol it is just classified as a firearm "the Shockwave is classified by the ATF as a “firearm” and available to shooters without having to buy a tax stamp or fill out paperwork" range365.com/mossberg-shockwave-gun-test#page-5

Scott, This is classified as a "firearm". It was manufactured just as is, no stock, no long barrel, not modified from original production form. Can be modified with "firearm" accessories. May not put a shotgun stock on this without $200 tax stamp and NFA registration.