Ok this glitch sounds dumb but it looks cool and is pretty effective. ok what it is is sentry guns inside each other and this gives a 360 range of the turrets with just the two and the more you have the more effective. there are two ways to do this. one you could get a sentry gun yourself if you get another from carepackages thats great.then you die or kill yourself but make sure the turret is still there when you respawn. finally just place the second turret inside the first but make sure its facing the opposit way or there will be two firing in the same direction. the other way is your friends can add to it but its more team benificial than to you because you dont get as many points. this may sound like it takes a while but it actually doesnt and is fairly simple if you can get 5 kills (4 with hardline) quickly. I got a 30 killstreak before i died and another 26 after that.