HK Army Performance Series – MP5 MID Pressure Piston (450-550psi)

The HK Army Performance Series – MP5 MID Pressure Piston (450-550psi) is built for players who want a simple, reliable way to tune or refresh their HK Army Performance Series regulator. Preset to deliver a 450-550psi mid-pressure output, this piston stack gives you a practical replacement option when your existing regulator is no longer holding a consistent output or when you need a different pressure range for your setup.

Its Belleville shim stack design keeps the package compact while providing precise, efficient pressure control. In practical use, that means a faster swap, less hassle on the bench, and more confidence that your air system will perform consistently once installed. The complete shim stack unit can be removed and dropped into the regulator without replacing the full assembly, which makes it especially useful for routine maintenance or pressure changes.

The brass piston construction and fitted O-rings are designed to support a secure, leak-free seal, helping maintain stable regulator behaviour during use. For players already running compatible HPA airsoft parts or maintaining an HK Army regulator, this is a straightforward component that solves a specific problem without unnecessary complication.

Always fully degas your air system before working on the regulator, then fit the correct piston for your setup and get your regulator back into service.