guess your talking about the laser guided bombs . using the unlockable laser designator within Recon class !
Found if you use both thumb sticks works really well just remember most people bail out once they hear/see they have been locked just go after them and leave the armour ..
good tip; if you see a burning vehicle' close to the target lock onto this then just aim for what ever you want within reason they never get the lock on alarm and they are dead
