M62 battle rifle

The BR662-SHR (Scoped Heavy Rifle) Battle Rifle was a battle rifle used by The Royal Allegiance, Ve'nek Dominion and United Nations Space Command before and during the Swarm War. The direct successor of the UNSC's previous battle rifle, the BR55HB, the BR662 was an enormous leap forward from the BR55, featuring a better accuracy, advanced weight reducing materials, frictionless barrel coating and a selective fire capability. The BR662 filled the capability void between smaller calibre rifles using the 7.62x51mm NATO, which lacked sufficient range and stopping power, and larger calibre sniper rifles chambered for the 14.5x114mm round, which lacked the portability of smaller systems. Utilising the 9.22x55mm high velocity, full power rifle round, the BR662 was able to engage targets at short, medium and semi-long ranges, its accuracy and stopping power great advantages against heavily shielded and armoured infantry targets. As a Battle Rifle, the BR662 fired a full-sized rifle round with increased range, accuracy and kinetic energy characteristics compared to assault rifles, giving a distinct advantage when facing hostile infantry forces. The rifle was also modular, allowing for a wide array of attachments to be added.

Technical Details
The BR662 was gas-operated with a rotating bolt, meaning it needed to be charged before the first round can be fired. The charging handle was used to chamber the first round, while the following rounds are chambered and fired and the casings ejected using the high pressure gas from the round fired. The handle was located on the left side of the weapon, positioned at the front of the slide during operation and slid back to enable reloading. The magazine was housed in a receiver mounted on the underside of the stock, while the release catch was located on the right side of the weapon. The weapon featured an ejection port for bullet casings on the right side of the weapon, though weapons were available with the port on the other side for left-handed users. Most of the Allegiance's ammunition utilised combustible bullet casings, meaning there was normally no jacket to eject because it had been reacted and contributed to the explosive reaction in the barrel (thus increasing the bullet's speed and therefore its range). The barrel itself was longer than the original BR55HB, meaning the bullet traveled for longer in the barrel, gained more spin from the rifling and as a result was more accurate, in addition to a higher muzzle velocity. The barrel end featured a three-way muzzle brake reducing recoil.

The weapon possessed numerous rails for mounting attachments, including on on its upper reciever, one on the underside and one on each side of the weapon.

Ammunition
The weapon was rechambered from the older, less potent 9.5x40mm UNSC round, for use with the Allegiance calibre 9.22x55mm, either HPSDAP (High Penetration Shield Depleting Armour Piercing) or HVS/AP-HE (High Velocity Shield/Armour Piercing-High Explosive) rounds. Due to the round's length and size a standard magazine could hold 32 rounds, though magazines were available that extended outside of the gun and allowed for up to 70-round mags.

The 9.22mm HPSDAP round was the pinnacle of Allegiance ballistics engineering- this was one of the last ballistic weapons ever produced by the Allegiance. The core of the bullet itself was tungsten carbide, giving it weight and as a result greater kinetic energy when impacting a target. It was surrounded by a titanium carbide penetrator with a depleted uranium tip. The bullet jacket was a polymer which was able to withstand the heat and pressure of being expelled from the barrel at high velocity. The jacket also gathered an electric charge while the bullet was in the air, aiding in shield depletion. The bullet acquired a greater charge and so the shield was depleted further at longer range. This unique ability was, however, near-useless as close range. As the war progressed, more advanced and potent forms of the ammunition emerged, though still based on the same principle.

Used more frequently was the HVS/AP-HE round. The High Velocity Shield/Armour Piercing High Explosive was the most common form of ammunition used on the battlefield, due to its high damage and multi role nature. it was in essence the basic, standard form of ammunition used when an all round munition was needed, and was highly popular throughout the armed forces. The round consisted of a deforming ballistic cap, a dense treated CVT/Austenitic alloy penetrator, a minute particle forcefield generator to neutralise shielding, and prefragmented tungsten carbide with a high explosive in the centre. The round was able to bypass any present shielding, pierce virtually any body armour and then fragment inside the target, with devastating results.

The weapon was capable of accepting both conventional chemically propelled ammunition, and the more powerful Electrothermal Acceleration system of round propellant. The Electrothermal Acceleration system used a plasma discharge rather than a chemical reaction to force the shell down the barrel. A high current, high voltage energy source was used along with a large Capacitor bank. Both were attached in series to the electrode system in the cannon's barrel. The capacitor was loaded with as high a voltage as possible. However, a militarily useful energy was achieved with as little as several kilojoules. The capacitor was then discharged. The gas in the gap between the electrodes would ionise, turning the non-flammable propellant into superheated conductive plasma. At this point, associated volumetric expansion would propel the projectile from the barrel at very high velocity.

The advantages of this method of propellant were clear. It increased the round's velocity by up to 480% over conventional techniques, aiding in accuracy and penetration characteristics. It used electricity as energy source, eliminating the need for explosive and vulnerable propellants. The power of the round could also be determined, unlike traditional methods. The more energy was supplied the faster the gases expanded, and the faster the projectile was accelerated. This made it possible to select any velocity desired and also allowed the projectile to reach speeds at which it would outrun the burn rate of a conventional propellant.

The weapon featured a standard mechanism that allowed for the firing of conventional, chemical rounds. In addition, the weapon featured an integral capacitor for use with Electrothermal accelerated rounds. These rounds featured specialised casings that contained gas for propellant and were otherwise identical to standard rounds, other than a specialised mechanism which allowed them to be fired using a conventional system. The magazine of these rounds would contain a high current, high voltage power source that, when used in conjunction with the in-built capacitor, allowed the use of electrothermal rounds.