Nordic Components MXT +2 Mossberg 590 Extension

The Nordic Components MXT +2 extension is the most popular magazine capacity upgrade for the Mossberg 590 series. The MXT line is modular: the +2 tube adds two rounds, but Nordic offers tubes from +1 through +9 that all use the same Mossberg-specific extension nut. For the 590 with an 18.5" barrel, the +2 brings capacity from 7+1 to 9+1 of 12 gauge 2.75" shells. Construction is anodized 6061 aluminum for corrosion resistance and weight savings, and the included extended spring matches the longer tube length to maintain reliable feeding.

Nordic Components is the OEM supplier for many factory extended-tube shotgun configurations, including the Mossberg 940 JM Pro Series, which means the MXT line carries the same engineering pedigree as factory upgrades. Installation is tool-less and reversible: unscrew the factory tube cap, slide the extension on, transfer the spring, and reinstall the cap. No permanent modification required.

The same Nordic extension nut also fits the Mossberg 835 and the 590S series. Capacities measured with 2.75" star-crimped shells; using 3" shells reduces capacity by one. For extensions of +4 rounds or longer, Nordic recommends adding a barrel clamp to stabilize the tube under recoil.