HPA Adaptors

A GBB pistol uses green gas, propane, or CO2 stored in the magazine to drive the slide. That works well in warm weather but starts failing below ~10°C — gas pressure drops, slide cycling becomes inconsistent, and rapid fire causes "cool-down" where the gas chills the magazine and FPS falls off shot by shot. An HPA adaptor solves this by replacing the gas magazine with one that takes a regulated air line from your tank instead.

Adaptors are platform-specific — a Hi-Capa adaptor doesn't fit a Glock and vice versa. The most common UK fitments:

Hi-Capa (Tokyo Marui and the wide range of TM-compatible clones — see the Hi-Capa Series)

Glock (TM Glock and licensed equivalents) also Action Army AAP-01 (the carbine-convertible duty pistol)

An adaptor on its own won't run a pistol — you'll need an HPA tank, regulator, and line (a 13ci compact tank works well for pistol-only setups). If you already run an HPA primary, the same tank, regulator, and line can swap to the pistol with a quick-disconnect fitting. For a purpose-built HPA pistol rather than an adapted GBB, see the Gate PTX.