The M16 rifle was created in the design office of the Californian company Armalite. It was developed according to the tactical and technical assumptions for the new rifle, issued by the American Infantry Board, which was to replace the worn-out and obsolete M14 rifles. The main designer of the weapon was Eugenie Stoner, who based the new design on his earlier work, the AR-10 rifle. The main change was the use of a different caliber, which was reduced from 7.62mm to 5.56mm. The cartridge used raised doubts from the beginning, today it is almost universally believed that it was not accurate, and the new rifle at that time should fire 6.6mm cartridges. After the modernization of the weapon, as a result of which the M16A2 version was created, the thread pitch in the barrel was changed, which allowed the use of a Belgian 5.56 mm cartridge, ballistically much better than the previously used cartridge of the same caliber produced in the USA. The first ten copies were tested on March 31, 1958. The field trials, conducted at two sites (Aberdeen Proving Ground - normal conditions; Fort Greely - arctic conditions), turned out to be successful, and the Committee recommended that the M16 rifle be used in the armament of the US Army. After the necessary corrections were made in January 1959, the Colt Patent Firearms Company, which acquired the license rights from Armalite, began serial production. Deliveries to the army began in 1961. Initially, the army received 85,000 units, while the US Air Force received 8,500. At the same time, the company designation was changed from AR-15 to M16. In 1967, the US government bought the patent rights from Colt. The M16A2 version was introduced into service in 1984. The rifle works on the principle of using the energy of gunpowder gases discharged from the barrel. The gases are discharged directly to the bolt carrier with a thin tube. Locking is performed by means of a rotary lock, the bolts of which enter the thrust of the bolt chamber, screwed on the barrel of the weapon. Interchangeable box magazines with a capacity of 20 or 30 cartridges, arranged in two rows, are used for power supply. The cartridge extractor and their ejector are located in the lock. Hammer action mechanism, with a covered stopcock. The trigger mechanism allows for single and series fire. Sight, dual-setting: 0-300 m and 300-500 m. The barrel of the weapon can be fitted with an M7 bayonet-knife or a device for firing blank ammunition. The "M203" grenade launcher can be hung under the barrel. Caliber: 5.56mm. Maximum shot distance: 3,600 meters. Maximum effective range: surface target: 800 meters; target target: 550 meters. Muzzle velocity: 853 m / s. Theoretical rate of fire: 800 rounds per minute. Magazine capacity: 20 and 30 rounds.
The M240 is a modern American 7.62mm medium machine gun. The total weight of the weapon (in the M240B version) is 12.5 kilograms, the total length is 126 cm, and the width is 12 centimeters. The effective range of this weapon when firing a bipod is 800 meters, and the maximum shot - about 3700 meters. The theoretical maximum rate of fire is 950 rounds per minute, and the muzzle velocity is about 850-900 m / s.
The M240 is essentially an American version of the Belgian FN MAG machine gun developed by Ernest Vervier in the 1950s. The principle of operation of this weapon was based on the discharge of gunpowder gases through the side opening in the barrel, and the designer used many solutions used in such rifles as the American BAR or the German MG42. Ultimately, a very successful weapon was created, which found its way into the equipment of dozens of countries around the world! For standardization purposes, the FN MAG was adapted to the use of NATO 7.62 x 51 mm ammunition. The same cartridge is also used by the M240, which entered service with the US armed forces in the 1980s, most often replacing the M60 rifle. The M240 rifle was used in combat, among others, in both Gulf wars (1990-1991 and 2003) or in the course of operations in Afghanistan (since 2001).