Lone Survivor is based on a true US Navy Seal mission in Afghanistan, which went terribly wrong. It was a much simpler, lower budget, more realistic affair than anything I had worked on for a long time, and relied on a lot of simple, old fashioned compositing work, rather than lots of CGI renders.
The main bulk of the work was muzzle flashes, blood splats and bullet hits, viewfinder graphics and gun scope views. I realised that I had never done a blood splat, or scope view, or a camera viewfinder effect before. They are such clichéd effects tasks I felt like I must have cheated to get this far in my career and manage to avoid them.
There were also some big matte painting shots, some CG helicopters and CG additions to wide shots of several airbases.
Even though the work was simple it was a satisfying project to work on. The VFX were not front and centre for a change. It was a very relaxed project, with no overtime or weekend work, and the final movie was pretty good too.
EDIT: Here is a reel of some of the shots I did in the movie