Ballistic Scope

Battlefield 3
The 12x ballistic scope is an optical zoom that's excellent for long range targeting. It's ideal for use in maps ranging from medium to large sizes. It is unlockable for all bolt-action sniper rifles and the M39 EMR. If you are a DICE employee, it is automatically unlocked for all weapons that have the option for equitable optics.

If a recon stays in one spot for too long, the lens will give off a very noticeable glint which will give away the position of the player.

For some reason, most Back to Karkand weapons unlocked by completing assignments come with a ballistic scope already equipped.

Ranging
NB: Every sniper rifle has it's own ranging. E.g. for M98B the first line below the center crosshair corresponds to about 500 meters, and the drop would be different than another, which may travel faster or slower.