Anyone provide me with some tips.
I'm stuck in the Silo bit, immediately after you run down the stairs, on veteran it's a nightmare.
That's the hardest part of the campaign imo, even worse than 'one shot one kill'.
No doubt you already know that a lot of luck and patience is involved, but it's very doable if you stick with it.
What I did was throw a flashbang and then a nade down each one of the two tunnels (flashbang left, flashbang right, nade left, nade right) and preyed that I got lucky in killing the two guards.
I then made my way down the the tunnel on the left and blasted the two guys that come running out (with my shotgun) which brought me to the long corridor with the guys who use wallhacks/who are obsurdly accurate and kill you with one shot, even when just peeping your head out!
At this point I switched to the silenced gun (the one that you start the level with?) and crept and crept until I could just barely see an elbow or kneecap and then shot and quickly moved out of the way.
After taking the first guy out (he's out of view - just to the right) two more will come running so stay put and blast them too. They'll still be one guy left at the bottom, and one or two to the left of the tunnel at the bottom but they arn't to much hassle to take out when compared to the prior enemies. As long as you make it to the silo doors with three minutes remaining you'll get another checkpoint, and it'll be easy sailing from there on in. GL.
ps this video helped me a little bit, dunno if you've seen it already?
http://uk.youtube.com/watch?v=Ic9wzAHL_rM
Edit: lol, I've just noticed that you're stuck in a different place to where I have explained.
The bit I'm talking about is a checkpoint after where you're stuck so the above may still be of some help to you.