[ucubed]

Sentry Gun doesn't count for your killstreak. If you can get to either your first killstreak at 7,8,9 you can quickly get to your 11 killstreak of an AC-130 or your Chopper Gunner...from there depending on how your team is killing theirs, you can force the other team to respawn only at 1 location and you can wreak havoc on them and there isn't much you can do about it...