[Brian McIlmoyle]

My 400 FPS with .20 GBBR shoots at 370fps with .30

There is far more Muzzle energy with .30 than with .20 out of the same GBBR due to the gas volume not being a fixed amount. Heavier BB stays in the barrel longer and so the valves remain open longer = more gas = higher muzzle energy.
( and also a marginally slower cyclic rate)

This is not the case with AEG, Muzzle energy is a constant because the volume of air propelling the bb is fixed by the cylinder volume.


My field gun is a GBBR that shoots just under 500 with .20 .. it shoots 440 with .30 it will break dry sticks as big as my finger. bushes are invisible to it.
and if it hits you.. you feel it