I'm noticing that most descriptions & reviews regarding FPS are done with .12, .20g BBs. Does anyone know if you can take the FPS info/ data from a 12 or 20g BB crono test and convert it to FPS for .23 & .25g? Is there some type of formula you can use to get that information without actually cronoing?


Thanks for all the info guys!
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This post has been edited by Bill229: May 12 2011, 11:19 AM

Yep, basically you are converting the velocity and weight you are shooting into Joules via the formula for kinetic energy. Since the energy is constant, you can find the new velocity with your new weight bbs.

For example:
A gun shoots 400fps with .20g bbs. I want to find how many Joules the gun is shooting, as well as what my gun would shoot with .28g bbs.

Formula: Kinetic Energy =.5 x mass x (velocity)^2 (mass must be converted to kg and fps must be converted to m/s)

.5 x (.20/1000) x (121.9)^2 = 1.49J

Now from here, we can find out the velocity using the same gun but with .28g bbs.

(v)^2 = 1.49/(.5 x (.28/1000)) =10642.9 <Take the square root =103.2m/s <convert to fps =339fps