SpudFiles

how do you find CB ratios? im building a new gun, cuz my old one had too many problems, and i want optimum power.

Measure the volume of your chamber and compare it to your barrel.

Well umm make your chamber a little more volume that your barrel.
And there is allways the spu wiki and GGDT...

the higher the chamber size the better your cannon will be. The projectile will be being pushed at a high pressure for a longer period down the barrel meaning higher velocities. example,

small chamber>valve opens>projectile is being pushed at 90psi 1/4 the length of the barrel>projectile is being pushed at 50psi 1/2 way> Projectile being pushed at 30psi 3/4> and leaves the barrel being pushed at by 10 psi.

large chamber> valve opens projectile is being pushed at 90 psi 1/4> projectile is being pushed at 85psi 1/2> projectile is being pushed at 80 psi 3/4> projectile is being pushed at 75 psi when leaving the barrel.

Also having a long barrel alows the air to be pushing it for a longer time picking its speed up.

If you have ggdt just use that to find the size of your C:B ratio

...but if the barrel is too long the most of the air has exhausted before the projectile has exited the barrel meaning the projectile leaves the barrel at relavtivly(sp?) the same speed as if it was a short barrel.

...unless you have a perfect fitting projectile and no holes in the barrel.