[ILLusion]

This is exactly why game hosts SHOULD be operating their games with a maximum WORK (JOULE) OUTPUT LIMIT, rather than an FPS limit.

I won't explain WHY it's doing this, as m102404 already covered this above, but I'm going to discuss what this means to you.

With spring and electric systems, the conversion is constantly linear. Meaning, regardless of how heavy your BB is, the work output level will ALWAYS be constant. If it shoots 1 Joule with a 0.2g BB (328fps), it will also shoot 1 Joule with a 0.36g BB (245fps). At the muzzle, the amount of pain felt by the target will remain exactly the same.

However, with a gas gun, if you set your gun to shoot and chrony 420fps with 0.2g (1.63 Joules) and proceed to head on to the field with 0.3g BBs shooting 420fps, you'll be shooting 2.45 Joules. To put that in to a number that you may understand better, you would be effectively shooting your targets with what is equivalent to 515fps with 0.20g BBs (at the muzzle.)

Also, because of the ballistic nature of heavier projectiles, they will carry that higher muzzle energy a lot further down range than lighter ammunition will. The end result is a dramatically increased damage level inflicted to your target.

That is causing unnecessary hurt and damage to your opponents... pain that I'm sure they WON'T appreciate.

Tune your gun for the ammo load you will be using, and don't deviate, for safety reasons. Breach of safety and consciously setting your gun to set it to such harmful levels is reason for any game host to ban you from a field.