play Stronghold at Fort Mercer. when on the attacking team, once you've captured the cannons at the 3rd checkpoint, instead of rushing towards the fort to capture the next object, stay and fire the cannons towards the objective flags to get a triple kill (this is a triple kill, not a triple kill streak achievement). you can usually see the name markers and can distinguish between your team and the enemy. be careful to not take out your own team, remembering, blue is your team, red is the enemy (your team can vote to kick you out of the session). if you can't snag one of the two cannons right away, you can pull out your carano rifle and snipe while waiting next to or behind one of the cannon gunners. usually the enemy gets the smarts to snipe out the cannon gunner and you should be able to jump on the cannon without waiting to long.