The 4.6x30mm cartridge is a type of ammunition used in the H&K MP7 PDW and by the H&K UCP pistol. It is designed to minimize weight and recoil while increasing penetration of body armor. It features a bottlenecked case and a pointed, steel-core, brass-jacketed bullet.
The round was designed as a competitor to the 5.7x28mm round developed by Fabrique Nationale. In head-to-head comparison of the two rounds, 4.6x30mm fired out of the MP7 is slower and offers slightly shorter range and reduced terminal ballistics than the 5.7x28mm fired out of the P90. SS195LF, with a 28 grain projectile, fired out of the P90 can achieve muzzle velocities of approximately 2500 ft/s.
The 4.6x30mm cartridge and the 5.7 x 28 have been criticized for having low terminal effectiveness. This claim comes especially from those who disagree with the "energy dump" theory of wound ballistics such as Dr. Martin Fackler and Dr. Gary Roberts. Kinetic energy manifests itself in human tissue in temporary stretching of tissue, which most tissue except for liver and neural tissue is able to withstand with little ill effect. Dr. Fackler and Dr. Roberts claim that the combination of permanent wound cavity and frequently insufficient penetration (the FBI recommends a minimum of 12 inches of penetration in ballistic gelatin) make these PDW cartridges terrible terminal performers. Slow motion videos show that the 4.6 mm bullet yaws at impact on soft tissue. This is because the mass centre of the bullet is behind the geometrical center causing the back to come forward at impact and therefore tumbling through soft tissue creating much larger damage . Due to the lighter weight of the bullet one can carry more ammunition and therefore increasing the fire power. Also, due to the lighter weight of the bullet, aiming in rapid fire is much easier as recoil depends much on the weight of the bullet. And because of the lesser diameter penetration power to armor is much higher as the crisat test proves.
The latest version ("Ultimate Combat") uses a 2g steel projectile at the same velocity, giving it a moderate edge in penetration over the 5.7x28mm cartridge. Terminal effectiveness is comparable to the 5.7 mm cartridge due to the increase in energy delivery.
- Penetration of a ballistic gelatin block at 50 m (20 % gelatin block 300 mm long) - 280 mm (11 in)
- Energy transfer through body armor at 50 m (1.6 mm titanium + 20 layers of Kevlar) - 220 J
- Energy transfer through body armor at 100 m (1.6 mm titanium + 20 layers of Kevlar) - 115 J
The same tests were performed on the 5.7x28mm round:
- Penetration of a ballistic gelatin block at 50 m (20 % gelatin block 300 mm long) - 230 mm
- Energy transfer through body armor at 50 m (1.6 mm titanium + 20 layers of Kevlar) - 180 J
- Energy transfer through body armor at 100 m (1.6 mm titanium + 20 layers of Kevlar) - 65 J
Muzzle Energies Compared:
Original 4.6 mm: 420 Joule, 310 ft·lbf (fired from MP7)
Standard 5.7 mm: 513 Joule, 379 ft·lbf (fired from P90)
2g Steel 4.6 mm: 525 Joule, 388 ft·lbf (fired from MP7)
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