PolarStar Airsoft MP5K CO2 Stock Adapter

The PolarStar MP5K Gas Stock Adapter allows MP5K platforms to be configured with either a self-contained HPA or CO₂ stock, or a traditional buffer tube setup. It is fully compatible with the Elite Force MP5K with CYMA OEM internals and can also be fitted to Tokyo Marui MP5K models, with only minor receiver modification required on those platforms.

Featuring internal 1-3/16 inch by 16 threads, the adapter accepts both Type 1 and Type 2 UGS and CGS stocks, making it possible to build a compact, fully self-contained SMG setup without the need for a remote air line. Alternatively, it can be used to mount a standard Milspec buffer tube, allowing the replica to be run with a remote line or even as a standard AEG.

The adapter installs using the existing body pins and acts as a direct replacement for the original end plate, requiring no gearbox modification and ensuring compatibility across HPA and AEG builds. It is also designed to work with Milspec receiver end plates, allowing the use of a wide range of sling plates.

Machined from a solid block of 6061 aluminium and finished with a durable anodised coating, the adapter is built for long-term use. A built-in 10-32 set screw tightens against the underside of the buffer tube to prevent rotation, keeping the stock securely indexed and rock solid during play.