The 5.45×39mm cartridge was developed in the early 1970s by a group of Soviet designers and engineers under the direction of M. Sabelnikov.

Cartridges like the 5.45×39mm, 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.

[3][4] 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 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.

[8] Kazakhstan plans on producing several types of small arms ammunition including the 5.45×39mm, with mass production expected to begin in 2024.

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.

(Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings the 5.45×39mm can handle up to 355.00 MPa (51,488 psi) Pmax piezo pressure.

regulated countries are currently (2014) proof tested at 443.80 MPa (64,368 psi) PE piezo pressure.

[2] Early ballistics tests demonstrated a pronounced tumbling effect with high speed cameras.

[15][16] 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".

Fragmentation of 5.45 mm bullets was observed predominantly in wounds of the lower extremities with fractures of long bones.

[18] Most organs and tissue were too flexible to be severely damaged by the temporary cavity effect caused by yaw and cavitation of a projectile.

As body armor saw increasing use in militaries, the original 7N6 standard service cartridge bullet construction was changed several times to improve penetration.

[26] 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.

Upon impacting a hard target, soft lead is pressed sideways by the steel penetrator, tearing the jacket.

7N22 boat-tail bullets weigh 3.69 g (56.9 gr) and can be identified by their red identification ring above the cartridge neck and a black tip.

[26] The 7N24 "super-armor-piercing" cartridge, introduced in 1999, has a stub cone nosed penetrator made of tungsten carbide (hard alloy VK8).

[26] The 7N39 armor-piercing cartridge, introduced in 2013, has a penetrator made of a tungsten carbide (92%) and cobalt (8%) alloy.

The round was loaded with a 4.4 g (67.9 gr) bullet containing a hardened tool-grade steel core with lead wrapping which is fired at a muzzle velocity of 879-895 m/s.

Accuracy of fire at 100 m (109 yd) (R50) is 35 mm (1.4 in)[26] The 5.45×39mm was developed by the Soviet Union for military use and it was not intended to create civilian weapons in this chambering.

[35] The civilian version of the Tavor TAR-21 rifle produced for the US market includes an optional 5.45×39mm conversion kit.

[37][38] It is unknown if Hornady plans to continue manufacturing this caliber, as the last confirmed lot number was released in 2021.

[40] The American firearms corporation Century International Arms offers Ukrainian made 5.45×39mm cartridges with steel casings and bi-metal (copper/steel) jacketed bullets under the Red Army Standard Ammunition brand.

rulings producing a maximal pressure of 302.7 MPa (43,900 psi) and keeps their qualities under various climatic and weather conditions independent of the season and at a temperature range from −50 to 50 °C (−58 to 122 °F).

[45][46] As of August 20, 2021, ammunition manufactured in Russia was added to the sanctions found in the CBW Act of 1991, (in retaliation to the Russian invasion of Ukraine) barring the importation of the majority of the cartridges listed above, to the United States.