Most guns are set to a certain pressure due to valve locking. Example Benjamin discovery is only 2000 psi. While the Benjamin marauder pistol with same air tube is set to 3000 psi. Once you fill past the recommended pressure, the valve locks and it will release air when the hammer strick the valve. But with a regulator, the valve will only see the pressure you set at. The max pressure now is how much your tube will be able to hold. Most companies test their air tube over 3 times it's pressure and it will not explode. So guns like the marauder, I installed a huma reg and fill to 4000 psi and shoot down to 1500 psi to get max shot per fill. Anyone else do the same? I know how dangerous hpa is but I'm confident my air tube will hold 4000. I wouldn't push it to 5000 or up even though I know it will hold it.