Weapon Name- HK Mp9
Round Type- .357 SIG
Over-all length- 415 mm (16.3 in) stock collapsed/ 638 mm (25.1 in) stock extended
Barrel length- 180 mm (7.1 in), 250mm (9.85 in)
Weight- 1.9 kg (4.19 lb), 1.15 kg (2.5 lb)
Rate of Fire- 650 RPM
Feed Mechanism- Detachable Box Magazine
Round Capacity- 20, 30, 45
Effective Range- 200 meters
Range- 300 meters
Accuracy- 2 MOA
Accessories- Picanty Rail
Quick switch firing mechanism- N/A
Scope/Sights- Picanty Rail
Muzzle Velocity- 700 m/s, 4.1 grams - 515 m/s, 7.5 grams
Firing System- MP7
Miscellaneous/electronic information- Essentially an MP7 refitted to fire .357 SIG rounds with 9mm armor piercing rounds.
Basic Information
Essentially an MP7 refitted to fire .357 SIG rounds with 9mm armor piercing rounds. The weapon is designed to use lightweight pistol cartridges, at approximately 8.1 grams, allowing The rounds are armor piercing, and have a high velocity, giving them incredible range for a sub-machine gun round, at 200 meters, and a maximum effective range of 400 meters. The rounds tendency to tumble and fragment enhances it's lethality, despite it's otherwise small size, increasing it's effectiveness. Although it is not as powerful as the 5.56mm, it is adequate in close quarters, particularly as a result of it's armor piercing capabilities, of which it can pierce a standard NATO CRISAT vest. Despite it's capacity to be used as a pistol, the weapon is quite large, although it is not the size of a full sized machine gun. Being slightly lighter weight, loaded, the weapon is approximately the same weight as an ordinary MP7. Being around 4.5 pounds, and capable of being held with one hand, the weapon fits somewhere between a pistol and small sub-machine gun. Variants of the firearm can be utilized in the XM29 series of weapons, of which use a longer barrel.
In 2002 and 2003, NATO conducted a series of tests with the intention of standardizing a PDW cartridge as a replacement for the 9×19mm Parabellum cartridge. The tests compared the relative merits of the 5.7×28mm cartridge and the HK 4.6×30mm cartridge, which was created by German small arms manufacturer Heckler & Koch as a competitor to the 5.7×28mm. The results of the NATO tests were analyzed by a group formed of experts from Canada, France, the United Kingdom, and the United States, and the group's conclusion was that the 5.7×28mm was "undoubtedly" the more efficient cartridge. Among other points, the NATO group cited superior effectiveness (27 percent greater) for the 5.7×28mm against unprotected targets and equal effectiveness against protected targets. It also cited less sensitivity to extreme temperatures for the 5.7×28mm, and cited a greater potential risk of barrel erosion with the 4.6×30mm. In addition, the group pointed out that 5.7×28mm is close to the 5.56×45mm NATO by its design and manufacture process, allowing it to be manufactured on existing production lines. The group also pointed out that 5.7×28mm firearms are more mature than 4.6×30mm firearms, and that the 5.7×28mm FN Five-seven pistol was already in production at that time, while the 4.6×30mm Heckler & Koch UCP pistol was only an early concept.
However, the German delegation and others rejected the NATO recommendation that 5.7×28mm be standardized, halting the standardization process indefinitely. As a result, both the 4.6×30mm and 5.7×28mm cartridges (and the associated weapons) have been independently adopted by various NATO countries, according to preference; both the P90 and Five-seven are currently in service with military and police forces in over 40 nations throughout the world. The 5.7mm round was found to be the superior round, and despite having slightly more recoil was still considered acceptable; in fact, it has 30% of the 9mm round, which is considered to be easily controllable. In fact, the 5.7mm has nearly 25% more energy than the 4.6mm round, which could explain some of it's superior performance characteristics compared to the 4.6mm (such as greater performance with soft tissue). While adequate, the 4.6mm was still too weak to be a serious competitor with the 5.7mm, which was already fairly weak in it's own right. Additionally, the 5.7mm is compatible with various other platforms, such as the P90 and Fn Five seven, and thus is better for standardization.
The weapon uses a polygonal cobalt chrome "flow formed" 8 groove 1:9 (1 complete turn in 9 inches / 278.6mm) right hand turn barrel; the barrel is made of an alloy that contains more than 50 percent cobalt. The barrel is roughly 13% heavier than standard steel barrels, but is more erosion and corrosion-resistant and is designed to retain high strength during long-term exposure to high temperatures. Cobalt alloys are frequently used in the aerospace industry, such as the hot-gas section of turbine engines. A proof of concept M240 7.62mm x 51mm NATO barrel, in practice, had 24,000 rounds test-fired through it, causing it to reach temperatures of 1,100 degrees, without failure. A steel barrel would have failed under such treatment.
