You've got a heavy rifle with the center of mass significantly above the point of rotation of the ball. The tendency is for the rifle to tip over. This sucks hard when you're trying to make a fine adjustment with your eye in the scope.
Cameras have the same problem. A leveling base is specifically designed to allow up to 15 deg of rotation in the pitch and roll axes (elevation and cant axes for rifles) independently of any tipping forces. You have to try it to understand how awesome it is. I haven't tried anything but a real RRS leveling head, so I can't say whether the ones made of Chinesium are any good.