To enable FOV ADS scaling in Battlefield 3, follow these steps: 1. Locate the "PROF_SAVE_profile" file in your Battlefield 3 installation directory. 2. Open the file using a text editor. 3. Search for the line that says "GstRender.FieldOfViewScale", and change its value to "1" for default FOV scaling. 4. To enable FOV ADS scaling, add the line "GstRender.FieldOfViewScaleADS 1" below it. Save the file and launch the game. Now, your FOV will scale when aiming down sights in BF3.