Cocking the bolt shouldn't be gritty. Is the grittiness there when you cock it without a magazine? There are many cases where the magazine doesn't sit perfectly in position, causing the oring on the bolt to rub against different parts of the magazine while advancing the pellet into the chamber.Accessing and removing the bolt is fairly simple. 2 screws holds the stock in place. Remove these 2 screws and a give it a bit of a tug to pop the stock off. Be careful when removing the receiver, as there is a little metal cylinder that sits freely in between the receiver and air tank. Unfortunately, there are also many cases where the air gauge is defective. Gamo typically will just send you a new air gauge. With all that said, the Urban is my favorite gun right now.
After watching this video I,m not sure you have a gage problem at all. In his review he said you will not see much of a drop in pressure till 50 shots. You said you only shot 30 shots. Watch video. Hope this helped. Fly
Urban guage is easy to change Shoot the gun until it's completely empty Remove action from stock Remove bad guage using 7/8 in wrench or socket Teflon tape threads on new guage and install on urban Reinstall action in stock Fill and check for leaks That's it 👍🏻👍🏻Gamoshooter