The 5.45×39 mm cartridge is a rimless bottlenecked intermediate cartridge. It was introduced into service in 1974 by the Soviet Union for use with the new AK-74. The 5.45×39 mm gradually supplemented and then largely replaced the 7.62×39mm cartridge in Soviet and Warsaw Pact service as the primary military service rifle cartridge. This change was made in order to compete with the American 5.56×45mm NATO for a light, flat shooting round.
History
The 5.45×39 mm cartridge was developed in the early 1970s by a group of Soviet designers and engineers under the direction of M. Sabelnikov. Further group members were: L. I. Bulavsky, B. B. Semin, M. E. Fedorov, P. F. Sazonov, V. Volkov, V. A. Nikolaev, E. E. Zimin and P. S. Korolev. The 5.45×39 mm couples a sensible case volume (1.75 ml) to bore area (23.99 mm2/0.2399 cm2) ratio with ample space for loading relatively long slender projectiles that can provide good aerodynamic efficiency and external ballistic performance for the projectile diameter.
The 5.45×39 mm is an example of an international tendency towards relatively small-sized, lightweight, high-velocity military service cartridges. Cartridges like the 5.45×39 mm, 5.56×45mm NATO and Chinese 5.8×42mm allow a soldier to carry more ammunition for the same weight compared to their larger and heavier predecessor cartridges, have favourable maximum point-blank range or "battle zero" characteristics and produce relatively low bolt thrust and free recoil impulse, favouring lightweight arms design and automatic fire accuracy.
The Soviet original military issue 7N6 cartridge variant introduced in 1974 is loaded with full metal jacket bullets that have a somewhat complex construction. The long boat-tail projectile's jacket is clad in gilding metal. The unhardened steel (steel 10) rod penetrator core is covered by a thin lead inlay which does not fill the entire point end, leaving a hollow cavity inside the nose. The bullet is cut to length during the manufacturing process to give the correct weight. The 7N6 uses a boat-tail design to reduce drag and there is a small lead plug crimped in place in the base of the bullet. The lead plug, in combination with the air space at the point of the bullet, has the effect of moving the bullet's center of gravity to the rear; the hollow air space also makes the bullet's point prone to deformation when the bullet strikes anything solid, inducing yaw. The brown-lacquered steel case is Berdan primed. Its length makes it slightly longer than the 7.62×39 mm case which measures exactly . The primer has a copper cup and is sealed with a heavy red lacquer. The propellant charge is a ball powder with similar burning characteristics to the WC844 powder used in 5.56×45mm NATO ammunition. The 7N6 cartridge weight is .
Tests indicate the free recoil energy delivered by the 5.45×39 mm AK-74 assault rifle is , compared to delivered by the 5.56×45 mm NATO in the M16 assault rifle and delivered by the 7.62×39 mm in the AKM assault rifle.
Military 5.45×39 mm ammunition was produced in the former Soviet Union, and in the GDR, and is produced in Bulgaria, Poland and Romania. In the former Soviet Union this ammunition is produced in Russia, Armenia, and Azerbaijan. Ukraine used to produce Soviet small arms ammunition before the Russians took over the Luhansk Cartridge Plant in 2014, but managed to resume production of 5.45×39 mm in 2024 and start producing 5.56×45 mm NATO ammunition as well. Kazakhstan plans on producing several types of small arms ammunition including the 5.45×39 mm, with mass production expected to begin in 2024.
Use in the Soviet-Afghan War When the AK-74 saw service during the Soviet-Afghan War, the original 5.45×39 mm 7N6 ball round quickly became known amongst the Afghan mujahideen as the "poison bullet": it caused more damage to internal tissue and organs in comparison to the 7.62×39 mm round used by the AK-47 and AKM (thanks to tumbling caused by the air space in the tip). Wounded fighters, often left untreated for days coupled with a severe shortage of antibiotics, quickly developed infections including gangrene, leading the mujahideen to mistakenly believe that the Soviets made use of poisoned bullets.
Use in Russo-Ukrainian War During April 2024 of the Russo-Ukrainian War, Ukrainian forces used predominately 5.45×39 mm ammunition according to American national Jonathan Poquette, a member of the Chosen Company, attached to the Ukrainian 59th Motorized Brigade. He cited a number of reasons, firstly an unorganised donation of rifles that fired NATO standard 5.56×45mm NATO. Some units received these weapons, others did not. Secondly, the donation of 5.56×45 mm NATO ammunition recently along with other aid from the West was lacking. The third reason is the fact that Ukraine was part of the Soviet Union, meaning that weapons firing 5.45×39 mm ammunition were more widely available. Further, Russian forces use it as their standard ammunition. Saying that "if you go and you attack a Russian position and you need to resupply, the Russians are usually going to have 5.45×39 mm."
Cartridge dimensions The 5.45×39 mm has a 1.75 mL (27 gr ) cartridge case capacity.
5.45×39 mm maximum C.I.P. cartridge dimensions.C.I.P. TDCC sheet 5,45 × 39
Americans would define the shoulder angle at ≈ 20.3°. The common rifling twist rate for this cartridge is 255 mm (1 in 10 inches), 4 grooves, Ø lands = 5.40 mm, Ø grooves = 5.60 mm, land width = 2.60 mm and the primer type is either berdan or small rifle.
According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings the 5.45×39 mm can handle up to Pmax piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. This means that 5.45×39 mm chambered arms in C.I.P. regulated countries are currently (2014) proof tested at PE piezo pressure.
Wounding effects
Early ballistics tests demonstrated a pronounced tumbling effect with high speed cameras. Some Western authorities believed this bullet was designed to tumble in flesh to increase wounding potential. At the time, it was believed that yawing and cavitation of projectiles were primarily responsible for tissue damage. The tumbling effect was caused by the hollow point of the bullet - as the bullet strikes a target, the core inside the bullet flies forward, shifting the center of gravity and causing the bullet to tumble. Martin Fackler conducted a study with an AK-74 assault rifle using live pigs and ballistic gelatin: "The result of our preset test indicate that the AK-74 bullet acts in the manner expected of a full-metal-cased military ammunition—it does not expand or fragment when striking soft tissues". Multiple x-rays done on human tissue support this assertion. The average frequency of fragmentation with 7N6 fired into extremities with injuries was 18%. This is compared to 57% with M193 5.56×45 in the same testing. Fragmentation of 5.45 mm bullets was observed predominantly in wounds of the lower extremities with fractures of long bones. Most organs and tissue were too flexible to be severely damaged by the temporary cavity effect caused by yaw and cavitation of a projectile. With the 5.45 mm bullet, tumbling produced a temporary cavity twice, at depths of and . This is similar to (but more rapid than) modern 7.62×39mm ammunition and to (non-fragmenting) 5.56 mm ammunition.
Military 5.45×39 mm rounds offer better penetration over (fragmenting) military 5.56×45 mm NATO rounds. Wounding Potential of the Russian AK-74 Assault Rifle. Martin L. Fackler MD. John S. Surinchak MA. John A. Malinowski BS. & Robert E. Bowin. The Journal of Trauma 1984. The Williams & Wilkins Co. Vol. 24, No. 3The Gun Digest Book of the AK & SKS: A Complete Guide to Guns, Gear and Ammunition. By Patrick Sweeney. Gun Digest Books, 2009. page 104–105Gun Digest Book of The Tactical Rifle: A User's Guide. By Patrick Sweeney. Krause Publications, 2011. page 151 Tandal AK-74S 5.45mm Bringing the AK into the 21st century with modular capability! By Charlie Cutshaw Photos by Doug Richardson. SPECIAL WEAPONS 2009. page 32-37
Terminal ballistics against body armor According to the Russian Defense Ministry's third Central Research Institute, the Russian military should consider switching back to improved 7.62×39 mm ammunition due to 5.45×39 mm penetration insufficiency against body armor at longer ranges. However, the change is yet to happen due to the development of the 7N39 cartridge with great penetration capabilities.
5.45×39mm cartridge variants
Enhanced penetration cartridges As body armor saw increasing use in militaries, the original 7N6 standard service cartridge bullet construction was changed several times to improve penetration. This resulted in the 7N6M, 7N10, 7N22, 7N24 and 7N39 variants.
The 7N6M (M—Russian: Модернизированный; Modernizirovanniy or "modernized") cartridge was introduced in 1987. In contrast to the original 7N6 unhardened steel rod penetrator the 7N6M rod penetrator is made of steel 65 and hardened to 60 HRC. The 7N6M boat-tail bullet can penetrate a 6 mm thick St3 steel plate at 300 m. 7N6(M) bullets have a red identification ring above the cartridge neck. The US Army's Ballistic Research Laboratory measured a ballistic coefficient (G7 BC) of 0.168 and form factor (G7 i) of 0.929 for the 7N6(M) projectile, which indicates good aerodynamic efficiency and external ballistic performance for the bullet diameter.The Case for a General-Purpose Rifle and Machine Gun Cartridge (GPC) by Anthony G Williams The rounds are loaded to produce a maximal pressure of .
The Bureau of Alcohol, Tobacco, Firearms and Explosives classified the 7N6 cartridge as "armor piercing handgun ammunition" on 7 April 2014, and, as such, it is illegal to import from Russia to the United States.
The 7N10 "improved penetration" cartridge was introduced in 1992. The 7N10 boat-tail bullet weighs and the weight of the lengthened sleeker steel (high-carbon steel U12A) penetrator made of steel 70 was increased to and the lead plug in front of it was discarded. The hollow cavity at the front of these projectiles was reduced significantly compared to previous 7N6(M) projectiles. In 1994 the 7N10 design was improved by filling the remaining hollow cavity in the projectiles front with lead and reducing the weight of the penetrator to resulting in a bullet weighing . Upon impacting a hard target, soft lead is pressed sideways by the steel penetrator, tearing the jacket. It has a ballistic coefficient (G1 BC) of approximately 0.351 and (G7 BC) of approximately 0.176. The 7N10 cartridge replaced the previous variants as standard Russian service round and can penetrate a 16 mm thick St3 steel plate at 100 m and 6B3TM ballistic vest at 200 m. 7N10 bullets have a violet/purple identification ring above the cartridge neck. The 7N10 and 7N6(M) cartridges have practically identical external ballistic characteristics, meaning they can share identical sighting lines and optics on firearms. The rounds are loaded to produce a maximal pressure of .
The 7N22 armour-piercing bullet, introduced in 1998, has a sharp-pointed steel penetrator made of steel U12A and retains the soft lead plug in the nose for jacket discarding. 7N22 boat-tail bullets weigh and can be identified by their red identification ring above the cartridge neck and a black tip. It has a ballistic coefficient (G7 BC) of approximately 0.180. The rounds are loaded to produce a maximal pressure of .