Scopes do not automatically make you more accurate when added to your gun. You have to zero your scope before it can do anything for you.
Steps to zero your scope:
1. Make sure your hop up is already tuned.
2. Install scope properly.
3. Shoot and adjust your scope in small increments until the point of impact converges with your point of aim.
Do not overtighten anything, including scope rings, screws, and any adjustments. Make sure the scope is level when you install it. Shoot at a distance such as 50 to 100 feet, something moderate in range but not the maximum range of your gun.
Watch the video by Fox Airsoft: