Re: I dont under stand the Coxial Design

The fill vavle is located behind the piston. When you fill up the cannon, the primary pressure pushes the piston towards the barrel. As you continue filling the cannon, the air gets across the piston, which is NOT 100% hermetically sealed, and fills the main chamber.
As the pressure increases the piston gets sucked to the barrel because of the enormous pressure differences.
When you open the exhaust valve, the pressure in the main chamber pushes the piston backwards from the barrel dramatically, and by that can push the projectile out of the barrel in gargantuan muzzle velocity.

I hope you understood me explanation, I tried to be clear. By the way, where are you from?