Intermediate cartridge

Heavy machine-gun cartridge: 12.7×99mm NATO, High power rifle cartridges: .300 Winchester Magnum, 7.62x51mm NATO (.308 Winchester), Intermediate cartridges: 7.62x39mm, 5.56×45 mm NATO, Rimfire cartridge .22 Long Rifle

An intermediate cartridge is a military assault rifle cartridge that is less powerful than typical full power battle rifle cartridges such as the United Kingdom .303 British, Russian 7.62×54mmR, German 7.92×57mm Mauser or United States .30-06 Springfield, but still significantly more powerful than pistol cartridges. As their recoil is significantly reduced compared to high power rifle cartridges, fully automatic rifles firing intermediate cartridges are relatively easy to control. However, even though less powerful than a traditional rifle cartridge, the ballistics are still sufficient for an effective range of 250–500 metres (270–550 yd), which are the maximum typical engagement ranges in combat. This allowed for the development of the assault rifle concept, which is a selective fire weapon that is more compact and lighter than rifles firing full power cartridges. The first known early intermediate cartridge to see service was the 10.4x38mmR Swiss used in the Vetterli rifle which gave it controllable handling and a then high-capacity magazine of 12 rounds. Predominant intermediate cartridges in mainstream circulation came around 50 years later to see widespread service was the German 7.92x33mm Kurz. Other examples include the Soviet 7.62x39mm used in the AK-47 and AKM series, and the .280 British round developed for the EM-2. The 5.56x45mm NATO cartridge is also an intermediate cartridge.

History

The first standard issue use of intermediate cartridges date back to the late 19th century with the introduction of the 10x4x38mmR round of the Swiss M1870 Vetterli rifle. This cartridge offered controllable handling when firing and a then high-capacity magazine of 12 rounds, predating the Lee-Metford rifle. Various other intermediate cartridges were used in World War I with the .345 Winchester Self-Loading and .351 WSL, these were in very limited use in firearms such as the Winchester-Burton M1917 automatic rifle and Winchester Model 1907.

The Second World War saw the use of the bolt action rifles such as the Mauser Karabiner 98k, the Lee-Enfield SMLE, the Mosin Nagant, the Arisaka Type 38 and Type 99 rifles, and during the early years, the Springfield M1903, as well as semi-automatic battle rifles such as the Gewehr 43, the M1 Garand and the SVT-40. These rifles weighed over 8 lb (3.6 kg), and they were longer than 40 in (1,000 mm) and as such inappropriate for close combat. They fired cartridges capable of killing out to 1,000 m (1,100 yd). In close quarter combat all the major armies began employing submachine guns such as the PPSh-41, Thompson M1928A1 and the MP-40, all of which fired pistol cartridges. Compared with the battle rifles these submachine guns could provide high rates of controllable fire but they lacked the power and longer effective range of the battle rifles.

Bolt action rifles in use at the time were considerably long and heavy, and their rate of fire was only around 10 - 15 rounds per minute. The bolt action rifles were effective up to 800–1,000 metres (870–1,090 yd) in the hands of a trained marksman,^{[citation needed]} but typical combat ranges were much shorter, around 150–300 metres (160–330 yd),^{[citation needed]} and most of the time they did not exceed 500 metres (550 yd). Therefore, the potential of the rifle ammunition at longer ranges was seldom needed.

"...if hasty wartime training was such that he [the infantryman] had no better than a fifty percent chance of hitting a target at 300 yards (270 m), there was no logical reason to give him a rifle and ammunition designed to kill at 2,000 yards (1,800 m)"

—Ian V. Hogg, Modern Small Arms

What was needed was a more compact, selective fire weapon firing a cartridge combining the power of a rifle and the controllability of pistol cartridges. The resulting cartridge would have the accuracy of the former for typical combat ranges, and the firepower of the latter at short ranges.

The first cartridge fulfilling this requirement may have been the Japanese 6.5x50mm Arisaka used by the Russian Fedorov Avtomat rifle since 1915 (the cartridge itself dates back to 1897). The Fedorov was arguably the first assault rifle. Later came the US .30 Carbine, developed as a weapon for officers and rear area soldiers unlikely to be involved in infantry assault, but needing a weapon more effective than a pistol. Soon after came the 7.92x33mm Kurz round developed by the Germans in 1938, which was a shortened version of the standard 7.92x57mm Mauser round, and was used in another candidate for first assault rifle, the StG-44. When the Soviets developed the AK-47, they already had an intermediate cartridge of their own, so they adopted the gas operation system of the StG-44, which was extremely reliable making it an ideal field weapon.

Since the 1960s NATO, the (former) Warsaw Pact, the People's Republic of China and other countries adapted relatively small sized, light weight, high velocity military intermediate service cartridges in the form of the 5.56×45mm NATO, Soviet 5.45×39mm and Chinese 5.8×42mm. These intermediate cartridges 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 impulse, favouring light weight arms design and automatic fire accuracy.

Performance

Typical characteristics of an intermediate cartridge are Kinetic energy ranges between 1,350–2,700 J (1,000–1,990 ft·lbf), muzzle velocities of 600–900 m/s (2,000–3,000 ft/s) and bullets of 3–9 grams (46–139 gr).

See also

• 

  Sturmgewehr 44 (Germany). Its development began in earnest with the Maschinenkarabiner project

• List of assault rifles

LE and Paramilitary

• 6.8x43mm 6.8 mm Remington SPC cartridge
• 6.5x39mm 6.5 mm Grendel cartidge developed for AR-15
• .22 Spitfire cartridge of the Iver Johnson Spitfire
• .221 Remington Fireball
• .300 AAC Blackout
• .375 SOCOM
• .450 Bushmaster
• .45 Raptor
• .458 HAM'R
• .458 SOCOM
• .50 Beowulf
• .500 Auto Max cartridge of the AR500
• 6.5mm Grendel
• 7.62×37mm Musang
• 7.62×45mm Pindad cartridge of the Sabhara/Police V1-V2
• 8.6 mm Blackout
• 9×39mm

Military Issue

• .30 Carbine (7.62x33mm) cartridge of the M1 carbine
• 7.92x33mm cartridge of the Sturmgewehr 44 assault rifle
• 7.62x39mm cartridge of the AK-47 assault rifle
• 7.62×45mm vz. 52 Czech round
• 5.56x45mm NATO cartridge of the M16 assault rifle
• 5.45x39mm cartridge of the AK-74 assault rifle
• 5.8×42mm DBP87 cartridge of the QBZ-95 assault rifle

Experimental

• .280 British cartridge of the EM-2 assault rifle
• 7.65x35mm French chambered in experimental French variant of StG 45(M) rifle
• 7.5x38mm chambered for the CEAM Modèle 1950 rifle
• 4.85x49mm Chambered for Enfield IW assault rifle which lead to the development of the SA80 series firearms
• 7.75x39mm GeCo the first intermediate round ever made, German experiment
• 7.65x33mm Argentine variant of German 7.92x33mm cartridge for use in Argentine copy of German Sturmgewehr 44 assault rifle

External links

• http://www.quarry.nildram.co.uk/Assault.htm