In France, an airsoft replica is not considered a weapon as long as its muzzle energy remains below 2 joules. Its sale and provision to minors are prohibited as soon as it exceeds 0.08 joules. FPS alone are not enough to judge the power of a Hi-Capa: the weight of the BB is also required. This guide explains the calculation and what to ask before buying.
This article is part of our Hi-Capa airsoft guide.
What the law says
| Muzzle energy | Status |
|---|---|
| Up to 0.08 joules | Toy threshold |
| More than 0.08 and less than 2 joules | Airsoft replica: trade regulated by Decree No. 99-240, sale and provision to minors prohibited |
| 2 joules and above | The object falls outside the scope of airsoft replicas and is subject to firearms regulations |
The Internal Security Code defines these replicas as objects that resemble a firearm and expel a non-metallic projectile with an energy of less than 2 joules. Decree No. 99-240 of March 24, 1999, regulates their trade, whether new or used. The relevant texts are cited below in the sources.
Playing fields and associations also set their own limits, which may differ depending on the type of replica. Ask the organizer about them before playing.
From FPS to joules: the calculation
FPS (feet per second) measures the speed of the BB. Joules measure its energy, which depends on speed and mass:
Energy (J) = ½ × mass (kg) × speed² (m/s), where 1 m/s = 3.281 FPS.
Example: a 0.20 g BB at 100 m/s (328 FPS) produces 0.5 × 0.0002 × 100² = 1.0 joule.
Why an FPS figure is not enough
The same speed produces different energy depending on the weight of the BB. Here is a conversion table showing the energy corresponding to a given speed:
| Measured speed | With a 0.20 g BB | With a 0.25 g BB |
|---|---|---|
| 328 FPS (100 m/s) | 1.00 J | 1.25 J |
| 350 FPS (106.7 m/s) | 1.14 J | 1.42 J |
And conversely, the speeds corresponding to 1 and 2 joules:
| BB weight | Speed for 1 J | Speed for 2 J |
|---|---|---|
| 0.20 g | 328 FPS | 464 FPS |
| 0.25 g | 293 FPS | 415 FPS |
| 0.28 g | 277 FPS | 392 FPS |
These tables are conversions, not measurements: a replica does not necessarily shoot at the same speed with heavier BBs. Only a chronograph measurement using your BBs will tell you what your Hi-Capa does.
What affects a Hi-Capa's power
- The gas: the higher the pressure, the higher the energy can be. See Hi-Capa Magazine: Marui, WE or AW, Gas or CO2.
- The temperature: in cold weather, green gas pressure drops, and so does power. See Hi-Capa in Winter: Which Gas and What Settings.
- The HPA regulator pressure: it can be adjusted and must be checked with a chronograph. See Hi-Capa HPA: Conversion, Pressure and Parts to Consider.
- Internal parts: the barrel, seal, nozzle and hammer group change how the gas propels the BB.
How to measure properly
- Use the BBs you actually play with.
- Record the gas, temperature and BB weight.
- Shoot several BBs and check the highest value, not just the average.
- Retake the measurement after every change of part, gas or pressure.
What to ask before buying
A custom build affects the parts that determine power. Before buying, ask if the replica has been measured with a chronograph and under what conditions: gas, BB weight, temperature. An announced power rating without these conditions does not tell you whether the replica complies with your field's limit. See Buying a Ready-to-Play Custom Hi-Capa: 7 Points to Check.
With us: every Hi-Capa from the Custom Lab is tuned and then tested with a chronograph before shipping to ensure it remains below the 2-joule limit for replicas.
Sources
- National Assembly, ministerial response on airsoft and minors (2020)
- Objects resembling firearms: Decree No. 99-240 (entreprises.gouv.fr)
Frequently Asked Questions
What is the maximum power of a Hi-Capa in France?
Less than 2 joules at the muzzle, like any airsoft replica. Beyond that, the object is subject to firearms regulations.
Can a minor use a Hi-Capa?
No, if the replica exceeds 0.08 joules: its sale and provision to minors are prohibited by Decree No. 99-240.
How do you convert FPS to joules?
Energy = ½ × mass in kg × speed² in m/s, where 1 m/s = 3.281 FPS. A 0.20 g BB at 328 FPS produces 1.0 joule.
Why is an FPS figure not enough?
Because energy also depends on the weight of the BB. 350 FPS produces 1.14 J with a 0.20 g BB and 1.42 J with a 0.25 g BB.
Does CO2 make a Hi-Capa illegal?
No, but the limit remains 2 joules regardless of the gas. The chronograph measurement is what counts.
Read also
- Buying a Ready-to-Play Custom Hi-Capa: 7 Points to Check
- Hi-Capa Magazine: Marui, WE or AW, Gas or CO2
- Hi-Capa HPA: Conversion, Pressure and Parts to Consider
- Hi-Capa in Winter: Which Gas and What Settings
Hi-Capas tested with a chronograph
Each build is tuned and then tested with a chronograph before shipping to ensure it remains below the 2-joule limit.
View Custom Hi-Capas → Have my Hi-Capa built
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