5.7x40mm AVA
| 5.7x40mm EC | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
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| Type | Rifle | |||||||||||
| Place of origin | Entente Cordiale | |||||||||||
| Service history | ||||||||||||
| In service | 1978–present | |||||||||||
| Used by | Sieuxerr Sylva New Tyran EC | |||||||||||
| Wars | Various | |||||||||||
| Production history | ||||||||||||
| Designer | Saint-Étienne Arms Manufacturer | |||||||||||
| Designed | 1977 | |||||||||||
| Manufacturer | MAS Manurhin Various other plants | |||||||||||
| Specifications | ||||||||||||
| Case type | Rimless | |||||||||||
| Bullet diameter | 5.7 millimetres (0.22 in) | |||||||||||
| Neck diameter | 6.5 millimetres (0.26 in) | |||||||||||
| Shoulder diameter | 8.3 millimetres (0.33 in) | |||||||||||
| Base diameter | 9 millimetres (0.35 in) | |||||||||||
| Rim diameter | 9 millimetres (0.35 in) | |||||||||||
| Rim thickness | 1.5 millimetres (0.059 in) | |||||||||||
| Case length | 40 millimetres (1.6 in) | |||||||||||
| Overall length | 56.4 millimetres (2.22 in) | |||||||||||
| Rifling twist | 1:12 | |||||||||||
| Primer type | Small rifle | |||||||||||
| Ballistic performance | ||||||||||||
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| Test barrel length: 500 millimetres (20 in) Source(s): Arsenal Munitions Test Range | ||||||||||||
The 5.7x40mm EC is a rimless, bottlenecked, center-fired intermediate cartridge family. Designed in the mid-1970s, the 5.7mm EC and 7x51mm EC cartridges and their weapons would become standardized across the Entente and Entente-aligned nations by the 1980s.
History
Development of an intermediate cartridge began in the 1950s following capture and analysis of former-Ostlandic small arms, notably the StG-44 and the 7.92x33mm Kurz, and other, smaller production run experimental weapons. Another weapon that the Sieuxerrian Army showed great intrest in was the Hallian M1 Carbine and its .30 Carbine cartridge. Testing of these two rounds would lead to a number of other experimental rounds. Along with this, a series of new rifles and light machine guns were beginning development. However, development slowed as instead a replacement for the various rifle cartridges that had been in service during the PSW was prioritized. Using new understandings of ballistic theory, a 7mm round was developed and put into service, the 7x51mm EC cartridge.
With the new 7mm round in service, development work began anew in the 1970s with a series of cartridges, many based off of foreign-designed rounds which were already in service at the time. As a design, it follows the standard principles of being a small-caliber, high-velocity cartridge, it exhibits superior penetration of standard-issue body armor at combat ranges however some have criticized its long-range performance, this has resulted in the 6×45mm Unified being developed and put into service, being similar in ballistic trajectory to the 7x51mm EC round out to 800~ meters while being lighter than it. The 6x45mm itself entered service in the early 2010s.
First accepted into service in 1978 with the new FA-MAS M.78 series of assault rifles, the Balle A featured a hardened steel core with a lead plug in a copper jacket with an air pocket in the nose. Later improvements saw the lead plug being moved further towards as the steel core was lengthened and further hardened. The newest round, Balle D, coming into service in the mid-2000s, features a long, hardened steel penetrator with no air gap in the nose, instead being filled with the soft-lead cap. As well, a “super-armor-piercing” round based on the Balle D known as the Balle DS trades the steel core with a tungsten-cobalt penetrator. The rounds are identified with a black lacquer ring instead of the standard red.