Battlefield 3 350m Sniper Headshot?

I am trying to complete one of the sniper assignments in BF3, but unfortunately I am a lousy sniper, and one of the requirements is that I make a 350m headshot with the L96. How is that even possible, short of pure luck? My longest headshot to date is 224m, and that one already felt like it was from one side of the map to the other. Having to account for bullet drop makes it even more difficult. How many notches up on the scope do you have to aim for a shot like that? The target’s head even with a 12x scope must look like a single pixel at that range. Does anyone have any tips that could help me out?

I suck at sniping too. Short of an aimbot, the best idea I can come up with is go with a friend on to a map that is empty and stand a distance apart and just take shots at one another. Eventually you’ll get a hit from the right distance.