What ammo are you using and at what distance are you shooting at?
Shadow 2s were sighted in at the factory using 124 Gr FMJ at 25 yards. Even if you were shooting a different type of ammo, it shouldn’t be shooting that far off unless there is something wrong (loose setscrew) on the rear sight itself. I have seen and experienced a loose set screw on mine and didn’t realize until I let a friend shot it. First thing he asked me after shooting it was, “did you check if the set screws are tight..” of course it wasn’t.