Don't call it a "shotgun" — or a "pistol!" The Mossberg 990 Aftershock is a compact, hand-held semiautomatic firearm with a 5+1 capacity for 12-gauge loads. Inspired by the success of the new-for-2017 pump-action 590 Shockwave, Mossberg engineers went to work on developing a gas system unique to the short-barreled, gas-operated system required for the 990 Aftershock. It is certainly portable but is it simply a trend or a useful self-defense tool in close-quarter environments? 

James Tarr reviewed the Mossberg 990 Aftershock for Guns & Ammo's October 2025 issue. Tarr was joined by Mossberg's Senior Director of Marketing Richard Kirk, Guns & Ammo's Managing Editor Jack Oller, and Editor-in-Chief Eric R. Poole, to report on his range experience and to seek more information about the evolution leading to one of the most versatile firearms on the market.