Famous Browning M2 was initially designed in USA as an aircraft gun, but in 1921 modernized for ground use and adopted as Model 1921 machinegun. In 1932 Model 1921 MG was modernized again and adopted under designation of M2. Later, after introduction of heavier barrel (for increased practical fire rate and number of rounds between barrel change) the gun was named M2HB. In M2HB, every barrel replacement must be followed with time-consuming procedure of headspace and timing ajustment, and only relatively recently QCB (Quick Change Barrel) kits were introduced. This kit may be used in any M2HB gun, allowing quick barrel change under the battle conditions. This version may be called M2HB-QCB or M2HQCB. For todays standarts, M2HB is quite heavy gun, and recently an US based company Ramo Defence introduced M2 Lightweight machinegun. M2 Lightweight is a new development weapon designed as a response to both ground and air forces requirement for a reduced weight .50 Caliber weapon. Utilizing the M2 Browning principles and almost 75% parts of the original M2, the weapon has been upgraded to include an adjustable buffer to vary firing rate, a patented quick change lightweight "Stellite" lined, chrome bore barrel with flash suppressor, "MAX SAFE" charging system, and trigger safety switch. M2 Lightweight weights only 27 kg (11 kg less than original M2HB), and has ajustable rate of fireof 550-750 rounds/min. M2 is a belt-fed, air-cooled, recoil operated full-auto only weapon. M2 operates wia short moving barrel. It could be used from M3 tripod (can not be used agains air targets), on M63 Anti-aircraft mount, it can be pintle, turret or coaxila mounted on combat vehicles or aircrafts. M2 is manufactured in USA by RAMO Defence, General Dynamics, in Belgium - by FN Herstal and by many other compabies. M2 adopted by US Armed forces and in more than 30 other countries.