First of all, I just wanted to say thanks to the devs; Insurgency: Sandstorm is a blast so far.
I had a small suggestion: it would be great if we could assign a toggle or hold key for lowering or raising the barrel of our weapons. This would allow us to look at friendly players without sticking a gun in their face. Obviously, this is not a huge gameplay problem, but it would help establish a bit of in-game courtesy and immersion.
The cool thing is that we already have a useful animation for this in the form of the ADS animation while line-of-sight is blocked by cover. The rifle is held vertically to indicate that you cannot fire. I would imagine that it would not take too much tinkering to build an assignable action for that animation.