NOTE:
Before people start commenting on this, know the facts below.
1. This is not a hack, it's a bug exploit.
2. It isn't JUST this guy who has infinite ammo and rapid fire, the exploit gives it to everyone in the match.
3. It's infectious and tends to spread around.
4. Everyone in the match is aware of the exploit causing this and can choose to leave the match if they so choose. It's so much fun you'll have a vard time putting the controller down.
Lastly, some players on the Xbox 360 network are communicating about this glitch which is actually an exploit mod that can be passed around easily like a virus. Thw way this works is the mod/glitch alters the Modern Warfare 2 map thereby disabling the ammo counter. See the videos below to believe it!