Thanks, have written a couple of useful things there, but it's not really what I'm looking for.

I intend to use the original chinese barrel "Lider44" 4.5 mm teeth in the future have no problems with ammo.

This is to look something like this:
http://www.fotosik.pl/pokaz_obrazek/b7ccbf65f7a2a592 ...

My first question is, what pressure is needed to push the lead pellet 4.5 mm for the barrel?

2 Has anyone design the right pump?