Projectile Details
Design InformationThe round is based off the 6.5mm Grendel round, using the exact 7.8 gram Nosler Partition round and round design. The round is essentially the same, except with the case removed and the propellant held together in a Hexagon or RDX binder, which causes the propellant to be far less sensitive then it would otherwise be (reducing the chance of a cook-off tremendously). Becuase the round is fired and fed electronically, there is also a much lowered chance of a cook off, and no hammer is required to set off the round. Instead, a battery, dumping a 17.5 volt charge specifically into the primer is used, and due to the exposed nature of the rounds, their relatively easy to set off with the conduction, or rather poor conduction of electricity. The only problem with the design is the need for an extremely powerful, somewhat small chamber (as the case usually absorbs a large amount the energy) but due to the flimsiness and reusable nature of brass cartridges and their intention to do so, a "Strong" chamber that can repeatedly be relied on to create a small enough high pressure area for the round to be fired in reality is relatively easy to do. The chamber it's fired from is usually made from ordinary high strength high carbon aluminum steel, and this tends to need replacement around every 10,000 rounds.
Bullet Composition
(The round used is most similar in apperance to the one that is the fifth from the left, or the second from the right.)
The round uses the 7.8 gram Nosler Partition round in particular, more or less for it's ability to penetrate and due to the fact that it doesn't expand or fragment in targets; as well as it's nearly perfectly balanced momentum to velocity ratio, muzzle velocity, and terminal ballistics. While ordinarily fragmentation or expansion is expected and even desirable in most rounds, it is illegal in the Geneva and Hague conventions, and use of these type of rounds would result in a disuse in most military applications. Despite it's lack of fragmentation, it's extreme ability to penetrate coupled with the fact that it yaws in tissue means that it is still an effective round; and it's ability to yaw in tissue actually increases it's permanent cavity in tissue and over-all the well balanced 7.8 gram projectile actually produces a more lethal round than it's fragmenting and expanding counterparts, to a certain degree. It is also effective at piercing body armor, being capable of penetrating low level MK. III body armor, but not the upper or mid level MK. III level body armor, making it extremely effective at Mk. II body armor penetration. Also, due to it's high penetration in flesh, the simulated compact flesh of the body armor causes the round to begin yawing early in tissue, producing an extremely lethal wound, even somewhat more lethal, when piercing level II body armor.
In a series of lab tests, "The 120 gr (7.8 g) Norma FMJ penetrated 16.5 inches (420 mm) before veering out the side of the block and impacting the support frame. No fragmentation was evident, but the slug is believed to have tumbled at about 7 inches (180 mm) with its maximum permanent cavity at 11 inches (280 mm). Lesions of more than 6 inches (150 mm) were torn through the top and bottom block surfaces. The bullet was fired from an Alexander Arms Tactical 14.5-inch (370 mm) AR-15 rifle at a range of 50 yards (46 m) with a chronographed impact velocity of 2,405 ft/s (733 m/s)."
Explosive 7.8 gram Nosler Partition Styled
High Explosive Incendiary/Armor Piercing Ammunition (HEIAP) is a form of shell which combines both an armor piercing capability and a high explosive effect. In this respect it is a modern version of armor piercing shell. The ammunition may also be called Semi-armor piercing high explosive incendiary (SAPHEI).
Typical of a modern HEIAP shell is the NM142 MP Mk 214 Mod 2 round designed for weapons such as heavy machine guns and anti-materiel rifles.
The primary purpose of these munitions is armor penetration and extended damage past pure kinetic energy, but unlike SLAP rounds (Saboted Light Armor Penetrator) which get their armor piercing ability from the propulsion of a 5.56mm tungsten heavy alloy bullet from a 7.62mm barrel using a sabot with much more energy than is usually possible from a 5.56mm round, HEIAP munitions use high explosives to "blast a path" for the penetrator. The special effect is developed when the round strikes the target. The initial collision ignites the incendiary material in the tip, triggering the detonation of the HE charge. The second (zirconium powder) incendiary charge will also ignite. This burns at a very high temperature, is not easily extinguished, and can last for 30 seconds.
The remaining element of the round is the tungsten carbide penetrator. This has a large amount of kinetic energy and will penetrate the armor as solid-cored armor piercing shot would. This will take some of the incendiary material through the armor. The MK 211 is claimed to penetrate up to an inch (25.4mm) of rolled homogeneous armor.
The triggering of the explosive charge is dependent upon the resistance of the target. If the target offers little resistance then the lack of frictional heating will prevent the incendiary from igniting and the high explosive from detonating.
Larger guns such as the British 30 mm RARDEN cannon fire APSE (Armour Piercing Special Effects) shells which are an armor piercing round with added HE effect.
This round is usually identified by a green over white paint tip mark. A rarer occurrence of a green–over red–over white paint mark scheme indicate the tracer version of this round. These tracer versions are usually only seen on cartridge feed belts in naval applications.
The headstamp on the casing can also help to identify the round as Raufoss and some common headstamps include, but not limited to: HXP89, WCC94, and FN91; or HXP, WCC, LC, or FN with different two-digit numbers as production year suffixes.
The round itself is a 7.8 gram container. It is nearly exactly the same weight and mass of the original round, although the dispersions of the densities of the material is vastly different. While obtaining slightly different ballistics due to the density change than an ordinary round of it's kind would, in an ordinary case, the minor difference in over-all ballistics path is mostly negligible (a .025 inch movement to the right at 600 yards). This is in part becuase the round detonates on impact, both igniting the 4000 degree zirconium, setting off the C-4 explosive, the force of both of these more than compensating for any change in accuracy, and also becuase both these explosions themselves send the carbon tungsten penetrater into the material at such a rapid velocity when combined with the initial kinetic energy that slightly changing velocity while in flight becomes close to irrelevant.
