The 590M is a box magazine-fed variant of the 590 shotgun. All the standard features of the 590 shotgun are present with the 590M (dual extrators, ambi safety, heavy-walled barrel, etc.), however the magwell features stabilizing ribs that engage with the magazine when loaded to ensure solid lock-up. The magazines for the 590M are manufactured by Adaptive Tactical, and come in 5, 10, 15, and 20-round capacities. They are a double-stack design, with hardened steel feed lips, overmolded grips, a self-lubricating polymer body, and an ASTM-A-228 music wire magazine spring.
The Mossberg 590M will be offered in both a standard and tri-rail model, the later of which includes a heat shield and ghost ring sights. Both models will come with a single 10-round magazine, and are currently in production.
