Originally Posted by ap27
I thought I read somewhere that GBBRs show an increase in FPS with heavier weights, due to a larger/longer buildup of pressure/gas behind the BB.
Am I mistaken?
yes you are... they show an increase in muzzle energy , which is a measure of the kinetic energy of the projectile.
muzzle energy in AEGs is fixed by the volume of air in the cylinder. so it drops as the projectile mass increases..
The force that a bb hits with is pretty much fixed with a AEG regardless of the weight of the projectile.
Heavier projectille gives you more stable flight over a longer distance, and greater penetration through leaf cover.
With gas guns .. the volume of propellant is not fixed.. with a heavier projectile, the time that the gas valves remain open and delivering gas is stretched out as it takes longer to accelerate the bb out of the barrel with a heavier mass..
so the heavier the bb the more gas is delivered to propel it.. the more Muzzle energy it will have upon leaving the barrel.