The 7.62×39 mm (also called 7.62 Soviet, formerly .30 Russian Short) round is a rimless bottlenecked intermediate cartridge of Soviet origin. The cartridge is widely used due to the global proliferation of the AK-47 rifle and related Kalashnikov-pattern rifles, the SKS semi-automatic rifle, and the RPD/RPK light machine guns.
The AK-47 was designed shortly after World War II, later becoming the AKM because the production of sheet metal receivers had issues when first initiated. This weapon is now the world's most widespread military-pattern rifle. The cartridge remained the Soviet standard until the 1970s. It was partly replaced in Soviet service by the 5.45×39mm cartridge, which was introduced with the new AK-74 rifle, and continues in service with the modernized current-issue Russian Armed Forces AK-74M service rifle, as well as the AK-12 rifle. In the 21st century, the 7.62×39 mm remains a common service rifle chambering, including for newly developed rifles like the AK-15.
History
On July 15, 1943, the Technical Council of the People's Commissariat for Armaments () met to discuss the introduction of a Soviet intermediate cartridge. The Soviet planners also decided at this meeting that their new cartridge was to be used in a whole range of infantry weapons, including a semi-automatic carbine, a selective fire submachine gun (in modern terms, a select-fire weapon firing an intermediate cartridge is considered an assault rifle), and a light machine gun. The job of designing the Soviet intermediate cartridge was assigned to a committee led by chief designer N.M. Elizarov (), assisted by P.V. Ryazanov (), B.V. Semin (), and I.T. Melnikov (). Elizarov collaborated closely with some leading weapons designers, including Fedorov, Tokarev, Simonov, and Shpagin. About 314 cartridge designs were considered theoretically, before narrowing the selection down to eight models that were physically constructed and tested. Most of the development work on the new cartridge took place at OKB-44, which was soon thereafter renamed as NII-44, and which in 1949 was merged with NII-61, itself merged with TsNIITochMash ("Central Scientific-Research Institute for Precision Machine Engineering") in 1966.
The first variant of the new cartridge was officially adopted for service after completing range trials in December 1943; it was given the GRAU index 57-N-231. This cartridge actually had a case length of 41 mm, so it is sometimes referred to as the 7.62×41. The bullet it contained was 22.8 mm long and had a core made entirely of lead. This bullet has a somewhat stubbier appearance than later 7.62×39 bullets, with its maximal radius being attained after only 13.01 mm from its tip, and it was lacking a boat tail. After some further refinements, a pilot production series of this cartridge began in March 1944."Патрон – основа оружия. Глава третья. Из истории автоматного 7,62-мм патрона образца 1943 г. (7,62х39)", Оружие 2005/9, pp. 21–44
After more detailed testing results became available, starting in 1947 the cartridge was tweaked by the Ulyanovsk Machine Building Plant to improve its accuracy and penetration. Initially, the boat tail had been omitted because the Soviet designers had assumed (incorrectly) that it would only make a difference at long ranges, when the bullet became subsonic, and the accuracy of the intermediate cartridge at these ranges was considered inconsequential. However, further testing showed that the boat tail improved accuracy even at shorter ranges, where the bullet was still supersonic. To maintain the overall mass of the bullet, after adding the boat tail, the ogival head section of the bullet was lengthened as well, making the bullet more streamlined overall. The maximum radius was now attained at some 15.95 mm from the tip and the overall length of the bullet increased to 26.8 mm. To preserve the total length of the cartridge, the case sleeve was shortened to 38.7 mm (and by rounding it is customarily referred to as 7.62×39.) Additionally, the new bullet had a core made of lead wrapped in low-carbon steel. The use of low-carbon (mild) steel was guided mostly by the desire to reuse some industrial equipment that was manufacturing the 7.62×25mm Tokarev cartridge rather than by bullet fragmentation considerations. This bullet was given the acronym "7.62 PS" (7.62 ПС). The "S" initially stood for "surrogate" (, ), but later the letter was taken to refer to the steel component (, ) of the core, which accounted for about 50% of the core volume. The 7.62×39 cartridge equipped with the PS bullet finally overcame all objections of the GAU in mid-1947, when it was ordered into series production and given the index 57-N-231S. Field tests of the round and the new prototype AK-47 were carried out at the NIPSVO from December 16, 1947, to January 11, 1948.
The design that was ultimately selected by the Soviets has more dimensional similarities to the GECO cartridge used in the Vollmer M35 than with the Polte round used by the later German Sturmgewehr. Some authors, including C. J. Chivers, have speculated that the Soviets may have had access to the works of GECO and Vollmer during 1940 when Hitler allowed a large number of Soviet engineers to tour various German armament factories. Anthony G. Williams, however, argues that the Soviet M43 round was so different that it was possible to dismiss the idea that it was a copy of any German round in existence at the time.
The 57-N-231S cartridge used a "bimetallic" (steel and copper) case. In the early 1960s, a "lacquered" steel case was introduced, and the new cartridge was initially given the designation 57-N-231SL. In an effort to simplify terminology, sometime thereafter the 57-N-231 designation was recycled to denote all steel-core 7.62×39 Soviet ammunition, irrespective of case build.
In the mid-1950s, Elizarov's team, now working at NII-61, developed a special subsonic bullet for the 7.62×39 cartridge. It was adopted for service in 1962, and given the army designation "7.62 US" (US stood for , meaning "reduced speed") and the GRAU index 57-N-231U. The subsonic bullet was considerably longer (33.62 mm) and heavier (12.5 g) than the PS bullet, and also had a different, non-layered core structure. The core of its head section was entirely made of tool steel, followed by another section entirely made of lead. The subsonic bullet also has a larger maximum diameter of 7.94 mm compared to all other 7.62×39 bullets that peak at 7.91 mm diameter; the larger diameter of the lead-core section was intended to provide a tighter fit to the barrel by better engaging the rifling grooves. The 7.62 subsonic ammo was intended to be fired from AK-47-type rifles equipped with the PBS-1 silencer and developed a muzzle velocity of about 285–300 m/s. For recognition, this ammo typically has the bullet tips painted black with a green band underneath.
After 1989, the regular (PS) Russian bullets started to be manufactured with a steel core with a higher carbon concentration and subjected to heat treatment. This change improved their penetration by 1.5–2 times. It is not possible to externally distinguish these bullets from the earlier, softer PS ones except by year of fabrication. At about the same time, tool steel was adopted for a normal velocity 7.62×39 bullet. Called BP, this bullet was developed in the 1980s and 1990s. It was officially adopted for Russian service in 2002 under the service name "7.62 BP", and with the GRAU designation 7N23. The BP bullet is claimed to achieve over three times the penetration of the PS bullet; it can defeat the Russian bullet-proof vest with designation 6B5 at distances below 250 meters. The BP cartridge has the tip of its bullet painted black. The BP bullet itself is slightly longer (27.4 mm) compared to the PS bullet, but has the same mass of 7.9 grams.
At the same 1943 meeting that decided the development new cartridge, the Soviet planners decided that a whole range of new small arms should use it, including a semi-automatic carbine, a fully automatic rifle, and a light machine gun. Design contests for these new weapons began in earnest in 1944.
Variants M43
The original Soviet M43 bullets are 123 grain boat-tail bullets with a copper-plated steel jacket, a large steel core, and some lead between the core and the jacket. The cartridge itself consisted of a Berdan-primed, highly tapered (usually steel) case which seats the bullet and contains the powder charge. The taper makes it very easy to feed and extract the round, since there is little contact with the chamber walls until the round is fully seated. This taper is what causes the AK-47 to have distinctively curved magazines (helping to distinguish AK-47s from AK-74s, which feed from a much straighter magazine). While the bullet design has gone through a few redesigns, the cartridge itself remains largely unchanged. The ballistic coefficient (G7 BC) of the M1943 pattern full metal jacket boat bullet is 0.138.
The complete solidity of the M43 projectile causes its only drawback—it is very stable, even while traversing tissue. It begins to yaw only after traversing nearly of tissue. This greatly reduces the potential wounding effectiveness of the projectile.
Type 56: Chinese mild steel core Chinese (Type 56) military ammunition (developed in 1956) is an M43-style cartridge with a mild steel core (MSC) and a copper-plated steel jacket. In 1956, the Chinese developed their own 7.62×39 mm assault rifle, also designated Type 56. It is a variant of the Soviet-designed AK-47 (specifically Type 3 and AKM) assault rifles. Production started in 1956 at State Factory 66 but was eventually handed over to Norinco, who continues to manufacture the rifle, primarily for export. Norinco developed and produced 7.62×39mm ammunition for the Type 56 rifle. The Chinese ammunition (as well as all other M43 ammunition) is currently banned from importation in the United States because U.S. federal law classifies the round as an armor-piercing handgun round. This classification is based on materials and bullet design rather than on empirical ability to penetrate armor.
Kal. 7,62mm×38 "Dutch" In the late 1950s West Germany was investigating the concept of an intermediate service cartridge (). As part of a ballistic study, the West German government commissioned reverse-engineered copies of the 7.62 mm M43 round. It was made for use in SKS rifles and RPD light machine guns that they had obtained from East German Army defectors. The Dutch firm (NWM) was contracted in 1958 to make the ammunition. Specifications based on captured samples were drawn up in April 1958 and production began in 1959.
There were two different cartridges commissioned. The first was a lead-core bullet (, or "soft core") with a gilding-metal jacket. It had a plain tip and red lacquer around the primer annulus to indicate that it was standard Ball ammunition. The other was an armour piercing bullet (, or "iron core") with a mild steel core and a gilding-metal jacket. It had black lacquer around the primer annulus to indicate it was armour piercing. (The early rounds were marked (Dutch: "armour", i.e. armour-piercing) on the packaging and had a black lacquered tip as per NATO standard markings). The brass cases were required to have a length between 38.36 and 38.7 mm, so the cartridge was designated the "7.62×38 mm". It was loaded with (German: "ball powder"] and used non-corrosive Sinoxid primers. The headstamp bore the metric designation (7.62×38 mm) at 12 o'clock, the 2-digit year at 4 o'clock, and the contractor (NWM) at 8 o'clock.
They were packed in 25-round cartons. The early cartons were marked in Dutch with black text on a plain white label. The later cartons were marked in German with a colored border (a red border for ball and a black border for armour-piercing).
M67