SRU SARB15 M4 Airsoft GBB Bullpup Chassis Kit – Tan

Transform Your M4 GBB into a Futuristic Bullpup Powerhouse

The SRU SARB15 chassis kit is a bold bullpup conversion designed exclusively for M4 GBB platforms. By shifting the action behind the grip, it significantly shortens the overall length while preserving barrel length — making it ideal for CQB and tactical scenarios where agility and control are key.

Broad GBB Compatibility

This kit is compatible with a range of popular gas blowback rifles including Tokyo Marui MWS, WE M4 GBB, and GHK M4 series. The design allows tight fitment, though minor adjustments may be required depending on receiver dimensions. It is not suitable for AEG platforms.

Lightweight, Durable Polymer Construction

Constructed from high-strength injection-molded polymer, the SARB15 offers a lightweight yet rugged shell weighing just 1090g. The material ensures durability without burdening the user, even during extended skirmishes or dynamic movement in confined spaces.

Optimized Layout & Accessory Compatibility

The top section provides a full-length 1913 Picatinny rail ideal for mounting red dot optics and magnifiers. Side and bottom rails accommodate lights, grips, and lasers, enhancing tactical adaptability. The bullpup trigger linkage system ensures responsive actuation despite the forward grip position.

Installation & Modular Adaptation

Installation requires disassembling the existing M4 body and integrating the internals into the bullpup chassis. Once mounted, the SARB15 provides enhanced weight distribution, centralizing mass towards the shoulder. Modular cutouts support heat dissipation and add visual aggression, true to SRU’s signature design.

Key Features

• Bullpup configuration for shorter overall profile
• Fits TM MWS, WE M4 GBB, and GHK M4 systems
• High-strength lightweight polymer body
• Extended top Picatinny rail for optics
• Side and lower accessory rails
• Weight: 1090g