Originally Posted by ILKx
so with the regulator, is every shot going to use only 100psi?
Sort of. Every shot is going to be propelled by 100psi, if that's what you mean, but every shot is not going to use 100psi of tank pressure. Higher pressure=lower volume, by the Ideal Gas Law and some other physics proofs I don't care to work out...so the higher the pressure the marker uses, the less gas per shot it will use. A marker shooting at 800psi is going to use less air per shot than a marker shooting 100psi because it'll take more air to accelerate the ball to 300fps than something with a much higher pressure.
Quick thing here, too: low-ends like Tippmanns can be converted to lower pressure (300-ish) which improves efficiency and consistency, but high-ends do work better at lower pressure anyways.
Hope that helped!