Nitrogen is a silly concept in paintball anyway. If you are smart you can build a marker to run VERY consistently on co2, even without a regulator. Just give it proper room and orientation to expand. In its gasious form, given you have a tank at least 1/2 full, co2 will hold very tightly around500 psi. If you gun is oiled properly and not full of debris, give it isn't made by the chinese it will fire within +/- 2 feet per second, better than a super gun on nitrogen/HPA with a $100 regualtor. I've done it, am currently doing it, and will do it again. Do yourself a favor and make sure the tank is tilted at least 35 degrees with the pin valve pointing up, this will keep the gasious co2 at the top of the full tank. Next, make a connection hose that is very long to give it proper room to expand in case you get into a rapid fire situation. When co2 flash boils it makes everything cold because it draws energy from its surroundings in the form of heat. Don't use expansion chambers, they create far too much volume and resistance in the system, use stainless steel braided hose.

Dont hate me because I also like paintball

I've always thought a spring-driven clip fed nerf gun would be nuts. If I ever get around to building what I have in mind I wil probably never use it in a game because of the ridiculous firepower that would surley kill the children.