B5 Systems MPS1555 Modular Platform Stock Coyote Brown

The B5 Systems Modular Platform Stock in Coyote Brown is a modern AR-pattern stock built for shooters who want adjustability without complexity. This composite-and-steel platform mounts via standard 1913 Picatinny rail and delivers the kind of ergonomic tuning you'd find on much higher-end builds—all without the price tag. Whether you're setting up a duty rifle, a precision build, or an all-purpose carbine, the MPS1555 adapts to your body and your mission.

What sets this stock apart is the spring-assisted cheekpiece. That integrated riser adds a half-inch of height when you need it, letting you index properly behind optics of various heights and accommodate body armor if you run it. The collapsible design gives you roughly two and a quarter inches of length-of-pull adjustment, so whether you're shooting in a tee shirt or over heavy gear, you can dial in a comfortable, repeatable shoulder position. Ambidextrous quick-disconnect sling mounts—both fixed and anti-rotation hardware—work from either side, and the nonslip buttpad keeps the rifle steady against your shoulder under recoil or during precision work.

Build quality is straightforward: durable composite construction handles the structural work, while color-matched steel hardware resists corrosion and won't rattle loose. The left-side folding hinge means you can collapse the stock when you need a compact profile—useful in vehicles, tight spaces, or whenever a shorter package matters. This is the kind of stock that rewards attention to detail; most shooters don't realize how much their accuracy and control improve once the stock actually fits them.

Key Features

• Spring-assist cheekpiece adds ½-inch of riser height for varied optic profiles
• Collapsible 2¼-inch length-of-pull adjustment for custom fit over layers or body armor
• Integral left-side folding steel hinge for compact storage and transport
• Ambidextrous fixed and quick-disconnect sling mounts with anti-rotation hardware
• Nonslip cushioned buttpad for stable shouldering and recoil management
• 1913 Picatinny rail attachment for universal AR platform compatibility
• Composite and steel construction resists wear and corrosion
• Color-matched hardware maintains uniform Coyote Brown aesthetic

Specifications

Frequently Asked Questions

Will this stock fit my AR-15 or AR-10?

The B5 MPS1555 attaches via standard 1913 Picatinny rail, so it works with any AR-pattern receiver equipped with a Picatinny-compatible buffer tube setup. Verify your upper and lower are compatible before purchasing.

How much can I adjust the length of pull?

The stock features a collapsible design with approximately 2¼ inches of adjustment. This range is enough to accommodate most body types and gear configurations—from a slimmer shooter in a light shirt to a larger operator in plates and a carrier.

Does the cheekpiece add a lot of height?

The spring-assist cheekpiece adds ½-inch of height. That's enough to clear most lower-mounted optics and improve your sight picture, especially useful if you're running a red dot, LPVO, or variable scope that mounts at standard height.

What's included in the box?

The product record doesn't specify what accessories or hardware are included with the stock. Contact us directly to confirm what comes standard and whether any additional Picatinny adapters or mounting hardware are needed for your build.