i also did it in the 1st go
heres how ! land on the roof of the Bunker with Lance in! And get your rocket launcher out ! Kill every muther fuker !

lol
But do NOT hit the bunker were lance is ! or MISSION FAILED
once you get in the bunker get your Colt out & hold In the circle button & keep tapping R1 to lock on to every one! till you drop the lot of em !