Battlefield 3 features a number of machine guns, ranging from smaller, lighter ones like the M27/RPK, all the way up to the heaviest ones like the Pecheneg and the M240. There are 2 starting machine guns in Battlefield 3, and 5 unlockable machine guns.
The M27 is the starting LMG for the US side, and is based on the M416 assault rifle, but is fitted with a heavier barrel and larger magazine.
The RPK is the starting LMG for the Russian side in Battlefield 3, and is based on the AK74, fitted with a heavier barrel and larger magazine.
The M249 light machine gun, also called the SAW (Squad Automatic Weapon), has been the main light machine gun of the US Army since its introduction in 1984. It is the first LMG to be unlocked in Battlefield 3.
The M240 is a Belgian designed light machine gun that has been used in the United States armed forces from the 1980s. The M240 is not only used as an LMG for infantry, but is used extensively as a mounted LMG on helicopters, cars, boats, and other vehicles as well.
The M60 is a tried and tested light machine gun and returns in Battlefield 3 as an unlock. The M60 offers great balance between range, accuracy and firepower.
The PKP Pecheneg is a relatively new Russian light machine gun, and is a modernized version of the popular PKM machine gun, with an improved barrel and internal mechanics. The Pecheneg is available as an unlock in Battlefield 3.
The Type 88 LMG, also known as the QJY 88, is a Chinese made general purpose machine gun introduced in 1988 and in use today. The Type 88 is one of the unlockable LMGS in Battlefield 3.
The MG36 light machine gun is based on the popular and reliable G36 assault rifle, but it uses a heavy barrel for increased heat resistance and accuracy. It was featured in Bad Company 1 and 2 and is expected to return in Battlefield 3 as an unlock.