I put a Huma reg in my Royale 400, and found the pressure scale on the reg to be way off. Also, it's possible you have accidentally got the reg set above your supply-side pressure, so the rifle is actually unregulated. When you remove the reg, drain the plenum by loosening the stock attachment screw housing, not the bottle adapter. If the plenum is pressurized, and you loosen the bottle adapter, it will suck the reg forward, and it can get stuck in the adapter in such a way that when you unscrew it, you will also unscrew the reg adjusting screw, mine actually totally unscrewed and came apart.