I don't think we were watching the same movie here pal:
Going off of the movie recollection, my experience with WH40k Apoc, a smidgen of info on BFG, and the old Aliens Boardgame:
They were the equivalent of EIGHT stormtroopers, TWO pilots, ONE unmodified and highly advanced combat servitor, with TWO civilian hangers-on, with two heavy bolters (Drake and Vasquez) three flamers that I noted (Wierzbowski, Dietrich, Frost), three Tarantula sentry guns, and bolters with underslung grenade launchers all around, with some assorted stubber pistols. One civilian there in a strictly advisory capacity who had past experience with the foes they /might/ face, they were informed, and an Administratum drone with no combat experience. They found a single equivalent whiteshield that started out unarmed and unarmored. Fourteen humans. Eight suitably equipped and designated combatants.
They had little to no understanding of the tactical situation where they were deployed, and they didn't have so much as an internal map of the complex until they were inside the complex. They were lead by an incompetent commander, and they had two thunderhawk transports at their disposal, carrying only chimeras that could deploy the whole squad and only wielded a single twin-linked heavy bolter. Their only goal upon arrival was to ascertain the situation of the colonists who the company has lost contact with, and reestablish communications. They were unable to contact their single glorified Firestorm Frigate for any sort of lance battery aid and only got the second Thunderhawk down in the last third of the movie. They were to be restricted usage of their flamers and bolter weapons totally in their first engagement, in which most of the casualties were sustained in the entire operation. The leadership was so terrible, the civilian had to drive the chimera into the reactor complex and extract the stormtroopers, after knocking out the Lieutenant of the stormtroopers.