Omega CF Tank fill pressure

Is the gun that you're filling regulated or unregulated? If it's regulated, just fill it above your regulator's set point. You won't get the full regulated shot count but if it's for hunting, then you won't need that much unless you have a lot of pest to deal with in one session. If you want to be above 250 bar then just have your Omega tank filled to 4500 psi.