XM13 Plasma Arc Carbine

"Small and lightweight, the PAC is portable hellfire"

- Anonymous designer

The , also known as just the Arc Carbine, or the PAC, is a carbine-style energy weapon, originally designed for the UNSC military, but now seeing widespread distribution across human space. One of the first human energy weapons to be mass produced, it has an infamous reputation as a lethal, if somewhat unpredictable weapon.

Uses
While shorter than most energy weapons used by the UNSC, the PAC makes up for its incredible lethality. Using a high voltage charge, it produces a slurry of high velocity plasma bolts, each carrying a huge electrical charge. This sudden burst of fire, while lacking in range, makes it deal for immediately terminating targets in short range fire fights. More often than not, it can drop a shielded Covenant warrior at twenty metres.

Because of its short length, and lightweight frame, its often used for close combat, clearing rooms and covering corridors in hails of fire. Unfortunately, it lacks range, making it perform poorly in open conflict, and relegating it almost entirely to close quarters and house to house fighting. Thanks to its small size, it's also deadly as a back-up weapon to a rifle.

The weapon has yet to see widespread use amongst the UNSC, and instead is limited mostly to special forces usage.

Operation
Despite the advanced nature of its munitions, the design of the weapon is relatively simple. It utilises an induction rod powered by the replaceable fuel cell to generate plasma, which is held in a vacuum reservoir. Exposed to a powerful electrical charge, the plasma takes on this charge. Once the charge is built, and the reservoir is filled with sufficient plasma, the magnetic claps holding it in place release like a shutter, closing several times in a millisecond, each time releasing enough plasma to form a bolt. Fed into the barrel, the magnetic sheath formed by the barrel (And powered by the very plasma its now firing) funnels and directs it, firing it at high velocity. The charge produces a signature high pitched whine, and radiates significant light from the heated components.

The gun is powered by a replaceable hydrogen fuel cell. Snapping on under the pistol grip, the standard cell powers the carbine for five shots, though high capacity batteries are in circulation. Integration is seamless, and as soon as it is attached it is in a position to power the weapon. The fuel cell is ejected by depressing two switches on either side of the cell, where it connects to the weapon itself. Once ejected, the safety latch moves to the 'safe' position. Once reloaded, the safety latch must be pressed to the closed position, which completes the circuit, making the gun active.

The PAC uses a sensitive two-stage trigger mechanism. The first stage charges the weapon, activating the induction rod and generating the plasma, and the second stage releases it. It is advised that the charge not be held too long as it threads the induction rod, heats up the gun and runs risks of reservoir rupture.

The weapon fires a rapid burst of seven plasma bolts, all seven leaving the barrel in half a second. Though it produces significant recoil, its lethality is unparalleled. Each plasma bolt is capable of punching through heavy armour, and the significant charge it carries shorts out shielding and electrical systems, as well as causing significant damage to the central nervous system of its target. Capable of over-penetrating armoured targets, its capacity for collateral damage is well known, removing its use from hostage situations.

The weapon itself is built on several recent 'wonder materials', such as tough polymers with high heat resistance, and metallic alloys with incredible heat tolerances, all of which are easy to manufacture and tool. It utilises an electronic fire control mounted in front of the trigger.

History
Originally developed in house at United Aerospace Systems, in their energy weapons division, it was envisioned as a high power carbine, capable of decimating heavily armoured targets in a single burst. Development began in 2554, though initial attempts proved fruitless, as the materials used in the prototypes were either insufficient or too expensive, limiting its applications. Despite this, static prototypes proved the model worked. A single high energy burst was capable of shredding advanced armour, with frightening ease. Its power interested members of the UNSC Ordnance committee, but the price tag turned them off. In response, the energy weapons division looked to the advanced materials division.

Working together, they began developing a number of materials that matched their needs, combining high heat tolerances and rigidity, even under temperature extremes. These materials took a number of years to perfect, and in their own right would become important products of UAE. Now with the correct materials, they began producing the low cost prototypes, several of which were disseminated to the UNSC for field testing. Initial tests proved positive, as the deadly little instrument was well liked by special forces operators, fighting Covenant forces in close quarters, though they lamented the charge up time, and the amount of light and noise it produced, before and after firing. However, it was during this phase that the UAE's patenting division revealed that they had failed to patent the technology in a timely manner, and it had been leaked to several rivals. As a result of this farce, the weapon was now not only produced by the UAE, but several rival corporations manufactured knock-offs.

Because of this, the weapon became incredibly wide spread, falling into the hands of planetary militia, pirates, mercenaries, terrorists and insurrectionists. Most models share common components and design details, resulting in a degree of interchangeability between models manufactured by different groups. Some models produced used inferior quality materials, and were dangerous to use for prolonged periods, while others used dangerous modifications that caused dangerous instabilities, but produced lethal results.