MW2, EBR with an ACOG, SPAS-12. Sleight of hand, stopping power and steady aim.
It was the chernobyl map near the end of the match, I'd gotten incredibly fed up with the whole enemy team persistantly camping inside the tunnel while my team with the lone acception of myself constantly running inside like meat to the grinder.
We were losing by a good margin when I got off my perch, ran down to one of the entrances, wasting the last of my shotgun ammo on ambushes the way there. Got inside, whipped out the sniper rifle and started plugging people. Aiming and hip firing, no bullets wasted, at one point I got 5 consecutive headshots. The enemy teams still piling in and explosions are all over the place and bullets are firing in from 3 directions and I don't know what's friendly fire and what isn't, shrapnel and dust all over the god damn place and I'm not going down.
I turned to one of the tunnels and 2 of my teammates finally make it in without dying, they've got machine guns and lmgs and crap and they're spraying next to me. 3 enemies run along the wall of the trench toward me. One jumps off the trench wall into the trench and I raise my gun to shoot him.
3 headshots...1 bullet, ended the match.
I got NBK, All Pro, finished the regular kill and headshot challenges for that sniper rifle, and I forget what else. It was a cascade of like 7 or 8 challenges but I couldn't even read them all because the match ended. ..There was a lot of bitching in that lobby.