Well done Andrew!
Very good considering you used no sound libraries. I really liked how you used little "sweetners" such as creaks and drips to emphasise the cuts, however i thought the low bass atmos got a little tiring after a while, i'm not sure if that was there all the time but its worth changing things up throughout the tracklay.
The gun effects were awesome and sounded very much like they were in a narrow space.
I agree with Joe that the footsteps and body armour needed to be more klinky and klenky but the sync of the steps were very good!
The breaths were really good but I think you need more of them, even on the mid/wide shots so we stay with the character, that is very important on a scene like this when you don't know whats lurking around the corner.
Really awesome job on the whole