There is no problem with your gun. It is how it works. If you watch matt dubber video, he talks about your problem. It is because of the dual reg and bigger 72cc power plenum. When you take a shot at higher power, air from your power plenum will be released to push the pellet or slug out. The reg will open and fill the power plenum until it hit the set pressure and the reg will close. When you shoot at lower power, the 72 PP is too big, meaning it holds so much air inside it. So when you shoot at lower power it uses so little air that the reg doesn't register fully that air even left. If it bothers you to shoot at low power and slow reg refill. You can fix it by using a small plenum. Like on the mk1 or mk2. Bigger plenum is made for higher power.