How do you use a bipod in battlefield 3

First, make sure that the bipod is armed. Then, while ingame, stand, crouch or lie next to a surface that is approximately the height of your gun. Next, hit the zoom button. The bipod should automatically deploy and stay there as long as you don't move your character (only use "look around"). The bipod stabilizes your gun while firing, which is especially needed while using the LMG's. If you get the chance to, it's a good idea to try. Note: If the bipod doesn't deploy or it deploys incorrectly, just move your character around a little and try again.