Map: Headquarters
...ok so here is the deal...EVERYONE plays an an automatic rifleman and use the A56R SAW (or whatever the hell the numbers are). have one person lay in prone in the spawn while others just wait around...have 2 other people lay in prone on the far right gate. (keep in mind the enemies can only come from one spot that you can just keep unloading on them)
the people on the right have the main job, while the spawn person is backup...NOW with the 2 people on the right hand gate...on lies on the right side and the other on the left....the person on the right shoots at the people when they come by...the person on the left cleans up whoever the person on the right didnt get, and if they miss, the person in the spawn gets em...BUT now comes the tricky part...
when the 3 people shooting run out of ammo...the replacement people should be waiting right behind them to go right to prone and take over their job....SO...(keep in mind the 3 people shooting, their ammo should last around 10 or so minutes)
you need to let a few mexicans get past so that when the person in the spawn kills them, the people that need ammo can get their gun. (*TIP* throw a smoke when going to retrive a weapon and make sure the people shooting COVER YOU!!)