A personal story: While playing Nova Logic's Black Hawk Down, I went counter sniping. My basic load was CAR15/M203 and claymores. I heard a sniper shooting, so approached him and set a clay down, right at his waist. He turned and got me, and then saw the clay. The sniper was stuck, if he moved, the clay would get him. So, this gave me time to respawn, and run right back to his spot. I never laughed so hard running back to get that sniper. When I got back to his spot, shot the clay and got him. Counter sniping is not going to get you into first place, but it will put a smile on your face every time you get a sniper.Remember the rule for sniper hunting, the closer you get, the greater your advantage is. At 1,000 yards, you are a moving target, at 50 yards, you become very hard target to hit. Once you are inside of 100 yards, keep a bead on the sniper, and be prepared to engage if he spots you. Never give up the advantage by switching to a knife at close ranges.
A good tactic is to get close, and use a shotgun or pistol, to shoot them in the back of the head. NEVER knife the sniper, it lets everyone know where you are at. You can also place a satchell charge on a sniper, back up a few feet, and detonate him. This should make him turn down the volume if he is using headphones. LAWs, RPGs, or AT-4s will allow you to launch at a sniper from long range, and close enough will count.