Your site may chronograph in Feet Per Second (fps) however, as far as the law is concerned you should be measuring the power in Joules. As per the Police & Crime Act, the legal limit is 1.3J for Automatic Weapons, or up to 2.5J for a Semi-Automatic (DMR/Bolt Action).
Airsoft Energy Chart:
The 2 charts below show the Joule Limits based on specific BB weights.
- The top chart is for fully-automatic RIFs & bottom one is for semi-automatic.
- Green indicates a safe joule limit
- Yellow shows a safe but narrow gap in restrictions.
- Red is over the legal limit.