I have made a similar one but I was smaller in just about every way. I will say I worked ok better on a lower pressure gun.
The basic idea is simple. When you fire your marker there is gas behind the ball. Gas or air expands and when the ball exits there is xxx amount of pressure. With ported barrels the gas escapes from the barrel through ports giving a lesser sound signature from the muzzle end.
Now as the ball enter the first chamber of the core gas or air will expand loosing pressure. Into the next chamber same thing and so on through the last. Now if we can get an engineering wiz to help out I'm sure it can be calculated what kind of pressure drops we may be looking at.