B5 Systems MPS-1554 Modular Platform Stock Flat Dark Earth - 1913 Picatinny Mount

The B5 Systems MPS-1554 Modular Platform Stock is a rugged, adaptable buttstock designed for rifle platforms equipped with a 1913 Picatinny rail interface rather than a traditional receiver extension tube. Finished in Flat Dark Earth, it brings B5's signature ergonomics and build quality to bullpup configurations, PDW setups, and other non-standard AR-pattern builds.

At its core is an integrated left-side folding steel hinge with color-matched steel hardware and a one-piece anti-rotation locking design. The stock folds flat against the side of the host firearm for transport and storage, then deploys with a solid, wobble-free lockup that holds position under recoil.

Shooter fit is handled by a collapsible length-of-pull adjustment offering 2-1/4 inches of travel, allowing the stock to be tuned for body armor, cold-weather clothing, or individual shooter preference. The adjustable spring-assist cheekpiece adds 1/2 inch of height for a repeatable cheek weld behind magnified optics and night-vision devices.

Constructed from durable polymer, the Modular Platform Stock weighs in at 16.8 ounces with overall dimensions of 8.06 inches long, 1.76 inches wide, and 4.67 inches tall. B5 Systems offers the Modular Platform Stock in Black, Flat Dark Earth, Coyote Brown, OD Green, and Wolf Grey, giving builders a color-matched option for nearly any rifle project.

Whether you're finishing a custom build, replacing a factory folder on a Picatinny-equipped platform, or upgrading a PDW or bullpup rifle, the B5 Systems MPS-1554 delivers the adjustability, durability, and refined ergonomics that have made B5 a trusted name among professional end users and civilian shooters alike.