Instructions
Play in any multiplayer match and complete the "Hard Landing" multiplayer challenge. You must shoot someone while he is climbing a ladder to complete this challenge. Hide out near a ladder that gets heavy traffic, wait for someone to climb it and shoot him.
Shoot an enemy while he is in mid-air after you complete the "Hard Landing" challenge. You don't have to start a new match to do this. If you're playing with a friend, instruct him to jump from a building while you stand below him. Keep your targeting reticule lined up with your target and wait for him to jump, and fire at him until he dies.
Wait around the foundations of short buildings that get a lot of traffic and wait for an enemy to jump from a building if you aren't playing with friends. Kill the enemy when the opportunity arises. Once the airborne enemy is dead, you will see an onscreen message indicating that you've earned the "Skeet Shooter" title.