| 5.45×39mm M74 | ||
|---|---|---|
5.45×39mm cartridge |
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| Type | Rifle | |
| Place of origin | Soviet Union | |
| Service history | ||
| In service | 1974–present | |
| Used by | Soviet Union/Russian Federation, former Soviet republics | |
| Wars | Afghan War, Georgian Civil War, First Chechen War, Second Chechen War, Yugoslav Wars | |
| Production history | ||
| Designed | 1972 | |
| Specifications | ||
| Case type | Steel, rimless, bottleneck | |
| Bullet diameter | 5.62 mm (0.221 in) | |
| Neck diameter | 6.29 mm (0.248 in) | |
| Shoulder diameter | 9.25 mm (0.364 in) | |
| Base diameter | 10.00 mm (0.394 in) | |
| Rim diameter | 10.00 mm (0.394 in) | |
| Rim thickness | 1.50 mm (0.059 in) | |
| Case length | 39.82 mm (1.568 in) | |
| Overall length | 57.00 mm (2.244 in) | |
| Rifling twist | 255 mm (1 in 10 inch) or 195 mm (1 in 7.68 inch) |
|
| Primer type | Small rifle | |
| Maximum pressure | 380.00 MPa (55,114 psi) | |
| Ballistic performance | ||
| Bullet weight/type | Velocity | Energy |
| 3.2 g (49 gr) 5N7 FMJ mild steel core | 915 m/s (3,000 ft/s) | 1,340 J (990 ft·lbf) |
| 3.43 g (52.9 gr) 7N6 FMJ hardened steel core | 880 m/s (2,900 ft/s) | 1,328 J (979 ft·lbf) |
| 3.62 g (55.9 gr) 7N10 FMJ enhanced penetration | 880 m/s (2,900 ft/s) | 1,402 J (1,034 ft·lbf) |
| 3.68 g (56.8 gr) 7N22 AP hardened steel core | 890 m/s (2,900 ft/s) | 1,457 J (1,075 ft·lbf) |
| 5.2 g (80 gr) 7U1 subsonic for silenced AKS-74UB | 303 m/s (990 ft/s) | 239 J (176 ft·lbf) |
| Test barrel length: 415 mm (16.3 in) and 200 mm (7.9 in) for 7U1 Source(s): [1] |
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The Soviet 5.45×39mm cartridge is a rimless bottlenecked rifle cartridge. It was introduced into service in 1974 for use with the new AK-74 assault rifle. It gradually supplemented then largely replaced the 7.62x39mm round in service.
The 5.45×39mm is an example of an international tendency towards relatively small sized light weight military service cartridges. Cartridges like the Russian 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 and produce relatively low bolt thrust and free recoil, favouring light weight arms design and automatic fire accuracy.
Contents |
The Russian original military issue 5N7 cartridge variant introduced in 1974 are loaded with full metal jacket bullets that have a somewhat complex construction. The 3.2 g (49.4 gr) boattail projectile has a gilding-metal-clad jacket. The unhardened steel core is covered by a thin lead coating 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 5N7 uses a boattail 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 39.37 mm (1.55 in) length makes it slightly longer than the 7.62×39mm case which measures exactly 38.60 mm (1.52 in). 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 WC 844 powder used in 5.56×45mm NATO ammunition. The 5N7 cartridge weight is 10.75 g (165.9 gr).
Tests indicate the free recoil energy delivered by the 5.45X39mm AK-74 assault rifle is 3.39 J (2.50 ft·lb), compared to 6.44 J (4.75 ft·lb) delivered by the 5.56×45mm NATO in the M16 assault rifle and 7.19 J (5.30 ft·lb) delivered by the 7.62x39mm in the AKM assault rifle.[2]
Military 5.45×39mm ammunition was produced in the former Soviet Union, German Democratic Republic and Yugoslavia, and is produced in Bulgaria, Poland and Romania. In the former Soviet Union this ammunition is produced in Russia, Kyrgyzstan, Uzbekistan and the Ukraine.
The 5.45×39mm has 1.75 ml (27 grains H2O) cartridge case capacity.
5.45×39mm maximum C.I.P. cartridge dimensions.[3]
Americans would define the shoulder angle at α⁄2 ≈ 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 A Feu Portatives) guidelines the 5.45×39mm case can handle up to 380 MPa (55,000 psi) 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.
Early ballistics tests done demonstrated a pronounced tumbling effect with high speed cameras.[4] 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 was primarily responsible for tissue damage. Martin Fackler conducted a study with an AK-74 assault rifle using live pigs and ballistic gelatin demonstrating that the 5.45×39mm round does not reliably fragment or cause unusual amounts of tissue disruption.[5] 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 100 and 350 mm. This is comparable to modern 7.62×39mm ammunition and to (non-fragmenting) 5.56 mm ammunition.
As body armor saw increasing use in militaries, the original 5N7 standard service cartridge bullet construction was changed several times to improve penetration. This resulted in the 7N6, 7N10, 7N22 and 7N24 cartridge 5.45×39mm variants.
The 7N6 bullet has a 1.43 g (22.1 gr) steel rod penetrator. Since 1987 this penetrator is hardened to 60 HRC. The latter 7N6 cartridge can penetrate a 6 mm thick St3 steel plate at 300 m and 6Zh85T body armour at 80 m. 7N6 bullets have a red identification ring above the cartridge neck.
The 7N10 "improved penetration" cartridge was introduced in 1992. The size of the steel penetrator was increased to 1.76 g (27.2 gr) and the lead plug in front of it was discarded. In 1994 the 7N10 design was improved by filling the air space with lead. Upon impacting a hard target, soft lead is pressed sideways by the steel penetrator, tearing the jacket. The 7N10 cartridge replaced the previous variants as standard Russian service round and can penetrate a 16 mm thick St3 steel plate at 300 m and 6Zh85T body armour at 200 m. 7N10 bullets have a violet/purple identification ring above the cartridge neck.
The 7N22 armour-piercing bullet, introduced in 1998, has a 1.75 g (27.0 gr) sharp-pointed steel penetrator and retains the soft lead plug in the nose for jacket discarding. 7N22 bullets can be identified by their red identification ring above the cartridge neck and a black tip.[6]
The recent 7N24 "super-armor-piercing" cartridge has a penetrator made of tungsten carbide. The 7N24 round is loaded with a a 4.15 g (64.0 gr) projectile containing a 2.1 g (32.4 gr) penetrator which is fired with a muzzle velocity of 840 m/s (2,756 ft/s) yielding 1,464 J (1,080 ft·lbf) muzzle energy.
Besides that the tracer cartridges 7T3 and 7T3M were developed. These bullets can be identified by their green marked tips. The 3.23 g (50 gr) tracer projectile has a shorter ogival profile and for 7T3 ammunition burns out to 800 m (870 yd) and for 7T3M ammunition ignites at 50 m (55 yd) burning out to 850 m (930 yd).
For training purposes the blank cartridges 7H3, 7H3M and 7Kh3 were developed. These round have a hollow white plastic imitation projectile. When these training rounds are used, the barrel of the gun is fitted at the muzzle with a Blank Fire Adapter to produce a gas pressure build-up for cycling the gun, as well as a breakup aid for their plastic projectiles.[7]
For instruction purposes the 7H4 training or dummy cartridge (which has longitudinal grooves) was developed.
For special purposes the 7U1 subsonic cartridge with a black and green painted meplat and CAP cartridge for underwater were developed.
The 7U1 subsonic cartridge weight is 11 g (170 gr) and is loaded with a 5.2 g (80 gr) projectile which is fired with a muzzle velocity of 303 m/s (994 ft/s) yielding 239 J (176 ft·lbf) muzzle energy. Accuracy of fire at 100 m (109 yd) (R50) is 35 mm (1.4 in)
| Cartridge designation | 7N6 | 7N10 | 7N22 | 7T3 (tracer) | 7Kh3 (training) |
|---|---|---|---|---|---|
| Cartridge weight | 10.5 g (162 gr) | 10.7 g (165 gr) | 10.75 g (166 gr) | 10.3 g (159 gr) | 6.65 g (103 gr) |
| Bullet weight | 3.43 g (52.9 gr) | 3.62 g (55.9 gr) | 3.68 g (56.8 gr) | 3.23 g (49.8 gr) | 0.24 g (3.7 gr) |
| Muzzle velocity | 880 m/s (2,887 ft/s) | 880 m/s (2,887 ft/s) | 890 m/s (2,920 ft/s) | 883 m/s (2,897 ft/s) | |
| Muzzle energy | 1,328 J (979 ft·lbf) | 1,402 J (1,034 ft·lbf) | 1,457 J (1,075 ft·lbf) | 1,259 J (929 ft·lbf) | |
| Accuracy of fire at 300 m (328 yd) (R50) |
75 mm (3.0 in) | 90 mm (3.5 in) | 90 mm (3.5 in) | 140 mm (5.5 in) |