Call Of Duty 5 : World At War
The bipod is available on completing the first Marksman challenge (Marksman I) for all MGs. It is more effective for MGs that can hold more ammo, as weapons such as the BAR, Type 99, and FG42 contain too little ammo and/or fire too fast with too little ammo to effectively use the bipod for prolonged periods of time.
To mount your machine gun, (if you have a bipod, that is), go up to any leveled surface e. g., a windowsill or sandbags, and a message saying "press and hold square to mount weapon" on the PS3, "press and hold X to mount weapon" on the Xbox360, "press and hold - (or A) to mount weapon" for the Wii, and "press and hold F to mount weapon" on the PC. You can only use the bipod when the message shows up, and you can no longer use it while prone.
Using the bipod on some machine guns like DP-28, Type 99, or BAR, decreases the machineguns' iron sight zoom. MG42 and Browning are apparently not affected by this.
The reticle will change into a large white cross when mounted, which will even appear in Hardcore. Recoil and idle sway are completely removed when the bipod is mounted, but there is also somewhat limited horizontal turning range. You will also fire 2 or 3 more bullets than normal, thus, if you are in a bipod position with the M1919 and pull the trigger quickly, which would normally result in one shot being fired, you will use up about 2 "bars" from the ammo counter but fire at least 3-4 bullets. Basically, mounting the bipod increases magazine capacity. The bipod is often used to create a distraction or provide extremely effective covering fire.
You might also notice that there are no "permanent" mounted machine guns in Call of Duty: World at War online play. These were removed in favor of the much more mobile bipods. Note, the bipod does not increase accuracy unless deployed.