i think the issue is that you need to look at the gun on rorke's leg a certain way-- like when the prompt comes up, the letter F and the hand/grab icon- it seems to want you to have the icon on his gun while you're pressing it and keep it there as he moves.
i'm not sure still though, because this doesn't work on regular or above-- i can SOMETIMES get it on recruit. most of the time, no matter how fast i press it or where i'm looking, it just plain doesn't work.
Well I managed to pass it. I just plugged in my 360 controller into the pc and mashed X and it worked. No need to look at the gun or anything from the youtube vids I saw. So give that a try if you have a game controller. Could be some confliction or something with my Logitech keyboard.