A properly working x-valve/RT valve will be switching bottle pressure to the top of the on/off at the point it needs to reset. That puts you at 800 psi at a minimum normally. The chamber pressures don't actually vary that much except with the bolt type, with the level 10 being about 50 or 75 psi higher (it's in here somewhere). Depending on velocity, bolts, paint and barrels, they run between 400-500 psi on the final dump chamber pressure, but a shutoff RT valve - ULT on/off will be sitting at bottle pressure.