M62 battle rifle

The M62 battle rifle was an air-cooled, magazine-fed selective fire rifle used by United Nations Space Command during the Swarm War. The direct successor of the UNSC's previous battle rifle, the , the M62 was an enormous leap forward from the BR55, featuring better accuracy, advanced weight reducing materials, frictionless barrel coating and a selective fire capability. The M62 filled the capability void between smaller calibre weapons using the , which lacked sufficient range and stopping power, and larger calibre weapons chambered for the .50 BMG and cartridges, which lacked the portability of smaller systems. Utilising the 9.5x60mm high velocity, full power rifle round, the M62 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 M62 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.
==History==
During the Human-Covenant War, the BR55 and its successor, the BR55HB, saw far more effectiveness against Covenant armour and shielding than the MA5C Assault Rifle. Mainly this was down to its calibre; the BR55 used 9.5x40mm ammunition, rather than the 7.62x51mm NATO rounds used by the MA5 family. This increased bullet size meant a higher impact energy on contact with the target, better accuracy and increased range, all of which improved over the 7.62mm round. The BR55 was at first issued to designated marksman within infantry squads, but later was issued far more widely, second only to the MA5C. Its selective fire modes, accuracy and increased range over the MA5 rifles, along with its ease of use, meant the BR55 would continue to serve in UNSC forces in various forms for decades to come. The BR55 had been designed based on the UNSC's previous squad marksman rifle, the , with major differences being rechambering of the weapon from 7.62x51mm, and general modernisation of the weapon's functionality and exterior.
In 2595, when the ageing BR55 came up for replacement, the UNSC issued a contract for a 9.5x60mm modular rifle that could engage targets at over a kilometre and harrass them at 1500 metres. Several competing companies put forward design prototypes, including Misriah Arms, Avalon Orbital and Hall Munitions. Misriah Arms opted for a fully modernised, heavily updated battle rifle named the XM62, that made use of various design and technical improvements since its predecessor was designed. Beating its competitors in several tests, the UNSC accepted the M62 into service with the Navy, Marines and Army as a designated marksman and service rifle.
The M62 was introduced gradually between 2602 and 2608, replacing the BR55HB and several license-built variants. It was still in service in 2633 when the Swarm War broke out; by this stage, it was clear that monetary issues, coupled with its effectiveness against Swarm armour, would keep it in service for the duration of the war.
==Usage==
Despite being a battle rifle, the M62's main usage, especially earlier in its deployment, was as a designated marksman rifle within squad-based combat. A small number of soldiers in a squad would be equipped with it to add a long-range rifleman capability to augment its firepower. Later on it was employed much more as a standard service rifle, seeing extensive usage by standard infantrymen, Marines and Special Forces units. Its long range in comparison to many other service rifles made it an excellent choice in large engagements; this, coupled with its large calibre round and relatively light weight, made it popular and widely used.
The M62's selective fire ability, in addition to its controllability and low recoil, meant it was a weapon useful at nearly all ranges. At long and semi-long range, or for increased accuracy, the weapon could be used in semi-automatic mode, and burst fire at closer ranges. A fully automatic mode of fire gave the user a powerful close and mid-range option; even though its usage was restricted to closer ranges, it was highly efficient against powerful close range enemies, and Reapers being a notable example.
==Design==
The M62 was gas-operated with a rotating bolt, meaning it needed to be charged before the first round could be fired. The charging handle was used to chamber the first round, while the following rounds were 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 barrel itself was longer than the original BR55HB, meaning the bullet traveled for longer in the barrel and as a result gained higher muzzle velocity and an increase in accuracy.
The barrel end featured a three-way muzzle brake reducing recoil, and was threaded to accept a suppressor. The weapon possessed rails on either side of the handgrip, the weapon's underside and the top side of the carrying handle, enabling a large amount of attachments to be quickly added according to required usage or user preference. A magazine release was located on either side of the weapon's external polymer casing near the magazine well. The rear of the M62's upper receiver, above the action and firing mechanism, accommodated a removable adjustable cheek rest that assisted in accurate long range fire. The weapon's upper receiver mounted a fore and rear foldable, removable ironsights that featured as standard on the weapon; they were frequently removed upon the use of more advanced optics. The weapon's handguard, sides and stock were constructed from lightweight yet strong and resistant polymer, as was the ergonomically-designed pistol grip. The upper receiver/carrying handle, rails and magazine assembly were constructed from high grade steel, while the barrel and firing mechanism were precision-machined titanium alloy.
Lighter than BR55, the M62 experienced lower recoil despite this, mainly as a result of several recoil-reducing methods. Several hydraulic buffers linked to the weapon's microprocessor accurately controlled recoil, reducing it considerably. The weapon also featured a venting system that recovered part of the gases generated by the round, and pushed it back in a space located behind the bolt during the cycle. The bolt 'bounced' on a sort of 'gas cushion' that acted as a buffer, dramatically reducing the weapon's recoil. It also featured energy absorption mechanisms in the buttstock, absorbing energy and reducing felt recoil. The weapon's bullpup nature meant that it was somewhat back-heavy; however, the recoil reduction mechanisms largely balanced this out, and its rather heavy barrel combated any muzzle climb. The barrel end also featured a three-way muzzle brake reducing recoil.
The rifle was modular, meaning that it was assembled in interchangeable sections that were easy to separate, in addition to its rails which accepted a wide range of attachments. The upper receiver or carrying handle, on which were mounted the iron sights and an attachment rail, was itself mounted on a rail and could be removed according to user preference, for example to reduce the weapon's size. This was, however, not an often used option as the fire mode selector, which was located on the left side of the upper receiver, needed to be relocated to a position just above the trigger; this was not a quick task and required the use of specialised tools. It also removed the vastly useful tactical computer. The cheek rest module could also be detached, which was often the case when the handle too had been removed. Attachments such as optics and sights could then be mounted onto this rail. Integrated into the upper receiver was a tactical computer which was heavily expanded from that of the BR55, no longer just showing tactical waypoints and ammunition reserves. It was able to link to the user's neural interface, allowing it to display, in conjunction with the user's Heads-Up Display, large amounts of information pertinent to the user's needs. Much of this comprised tactical information about the combatant's immediate battlefield surroundings, including but not limited to friendly and hostile positions, topographical and meteorological data and current commands, objectives and targets.
==Ammunition==
The M62 used 9.5x60mm ammunition, which was a full sized rifle round utilised in battle rifles and medium (or general purpose) machine guns. The round was larger than most cartridges used in infantry rifles; this meant that the M62 suffered increased recoil than weapons such as the MA6 assault rifle. However, this increased mass gave it increased kinetic energy, allowing it to impart significantly more damage to the target than the 7.62x51mm NATO round, as well as having increased range and muzzle velocity. These characteristics made it suitable for use in longer ranged weapons such as battle rifles.
The weapon, like nearly all UNSC weapons, utilised caseless ammunition, which had several advantages over traditional cased ammunition. This was a major change from Great War-era weapons, which utilised rounds which contained propellant inside metal casings. From the conclusion of the Human-Covenant War onwards, the UNSC worked on increasing the lethality of its infantry firearms; aside from the development of directed energy weapons, one element the UNSC looked at was the application of caseless ammunition. This was already used with operational success in the M7/Caseless Submachine Gun, though was limited to this weapon and not available in other calibres. Developments in technology, however, allowed the widespread adoption of caseless ammunition from around two decades after the war onwards, with newer replacement weapons discarding more traditional ammunition.
Unlike experimental caseless munitions of the late 20th century, the M62's ammunition maintained a tolerance similar to traditional, cased bullets. This was achieved by the propellant being coated in a thin layer of water, heat and dirt resistant coating. This also allowed rounds to be handled and manually loaded, as well as improving their 'drop resistance' or shock tolerance significantly. This also increased its shelf life considerably. These qualities were present in the M7/C Submachine Gun's ammunition, and carried over to the UNSC's next generation of caseless weapons.
Caseless ammunition offered several advantages. The most noticeable was an increase in muzzle velocity; not only was more propellant available per bullet with the caseless system, the propellant released significantly more energy when combusted. This higher muzzle velocity led the BR60 to deal noticeably increased damage to the target in terms of kinetic effects; this also markedly improved its armour and shield penetration characteristics. The 9.5mm round's muzzle velocity was typically two to three times higher with caseless ammunition than traditional cased types, making it significantly more effective than its more traditional predecessors and meaning even assault rifles were capable of taking on shielded and armoured Covenant infantry. It was largely this increase in lethality that convinced the UNSC to maintain ballistic weapons for the bulk of their weapons, rather than developing and adopting plasma weapons of their own.
Caseless ammunition also reduced the complexity of the BR60's internal mechanisms, as there was no need for extraction and ejection of spent casings. As the overall round was smaller, it allowed for larger capacity magazines, and its significantly reduced weight increased the amount of ammunition a soldier could realistically carry.
The 9.5mm bullet was actually embedded inside the solid propellant 'block'; it, the bullet and the primer were held together by a combustible glue. When fired, everything in the chamber save the bullet fully combusted, leaving no residue in the chamber and propelling the bullet down the barrel. The propellant itself was an advanced solid, plasma-based substance similar in composition to that of the the experimental M634 HP-SAP, which gave high muzzle velocity; this in turn increased lethality on contact with the target. The block was highly resistant to temperature, which prevented it from combusting prematurely, for example on contact with heat inside the weapon, or external heat sources.
There were numerous forms of 9.5x60mm ammunition available to the UNSC, each differing in usage and effects. This varied from the simple and cheap to the complex and expensive to manufacture. The most commonly issued and utilised round was the M636 S/AP-HE, or Shield/Armour Piercing-High Explosive, which was a balance of potency and cost. Specialised ammunition, such as the M635 SAP-HEI, was generally only issued to high priority units and special forces, while forms such as the M603 Jacketed Hollow Point specialised to a degree where they were limited in their effectiveness, and as a result were not commonly issued.
*: The former standard round issued with 9.5mm calibre rifles, the M634 HP-SAP (or High-Powered Semi-Armour-Piercing) was largely superseded by more advanced rounds, especially for use with the modernised M62 battle rifle. The round featured a lightweight ballistic cap, which deformed on impact with the target and offered superior aerodynamic properties to the projectile in flight. The bullet's exterior was composed of lead, which fragmented and expanded outwards upon impact with a target. The internal penetrator was comprised of tungsten carbide alloy; between this and the ballistic cap was a small space or 'hollow', into which the penetrator would force itself upon impact with the target (this also expanded and fragmented the bullet's lead jacket, causing expansive and grievous wounds). Later iterations of the round also featured a polymer which coated the bullet, acquiring an electric charge in flight and assisting in shield depletion.
*M635 Semi-Armour Piercing-High Explosive Incendiary: The M635 Semi-Armour Piercing-High Explosive Incendiary, or SAP-HEI, was an ammunition type combining both an armour piercing and an explosive/incendiary capability. The bullet's tip was filled with a highly incendiary chemical, which burned at several thousand degrees upon impact with a target, damaging or melting armour and heavily affecting shields. Behind this was a high explosive component which detonated immediately on impact with a target, further damaging the area. Behind this was a solid core penetrator of depleted uranium, held in a backing 'cup' of steel. The components were held together in a copper or lead jacket. Upon hitting a target, the incendiary and explosive properties would damage the target area, aiding considerably in the depleted uranium's penetration into the interior. The penetrator featured a self-sharpening tip and was itself pyrophoric, meaning that it ignited upon impact with the incendiary material. It then punched through any remaining armour, having been ignited at this point and also carrying with it any remaining incendiary material from the tip. Effects on the target, especially if it was organically-based, were catastrophically damaging; the round would typically bypass any present armour (following rapid depletion of shields) and propel an incendiary penetrator and secondary incendiary material into the target's innards. However, the round's complexity in design made it expensive and its use was usually reserved for special forces and select few line units.
*M636 Shield/Armour Piercing-High Explosive: The M636 Shield/Armour Piercing-High Explosive, also known as S/AP-HE, was the most common and effective type of ammunition employed in the 9.5x40mm calibre. The bullet itself was coated in a polymer which acquired an electric charge while in flight, aiding the bullet's kinetic energy in depleting shielding and, although it had little effect on armour, increased the bullet's drain on shielding by roughly half. The further the bullet travelled in the air, the greater the charge it acquired, so this effect was at its most potent at longer ranges and nearly negligible at extreme close range. The tip of the round consisted of a deforming ballistic cap; a lightweight element which crumpled upon impact with a target and gave the bullet superior aerodynamic characteristics. The bullet's armour-piercing core was a 'CVT' (Chromium Vanadium Tungsten) and Austenitic Steel alloy with a self-sharpening tip; when it fractured upon impact, it would do so in a way that the remaining element was still a sharp point. Behind this was a pre-fragmented block of 'TC3' alloy, composed of tungsten, cerium and copper carbide, with a delayed action fuze in the centre. This alloy maintained similar incendiary and pyrophoric properties to uranium, though without associated radiological effects. A milisecond after the bullet's penetration of the target, the fuze would activate; this fuze contained a plasma-based high explosive compound, which explosively fragmented the pre-weakened TC3, in turn heavily damaging organic structures and internal organs. As a secondary function the TC3 was incendiary, causing severe secondary damage to soft targets.
*M637 Jacketed Hollow Point: The M637 Jacketed Hollow Point (JHP) 
*M638 Tracer: The M638 Tracer
*M639 Armour Piercing High Explosive: The M639 Armour Piercing High Explosive round was an effective armour defeating round, used as a cheaper alternative to more expensive semi-armour piercing high explosive incendiary (SAPHEI) ammunition. The bullet's tip was composed of a hollow, lightweight ballistic cap which deformed on impact, and improved the bullet's ballistic properties. Behind this was an armour piercing penetrator composed of CVT (Chromium Vanadium Tungsten) and Austenitic steel alloy, with a self sharpening tip. The remaining length of the bullet was comprised of 'stressed' steel; the interior of this steel was hollowed out and contained explosive filler and a delayed action fuze. Shortly after impact this would detonate, fragmenting the steel and causing effects similar to a miniature fragmentation grenade, albeit designed to detonate inside an organic body.
*M640 High Explosive Squash Head: The M640 High Explosive Squash Head round, or HESH, was designed to deal damage to a target without needing to defeat its armour, thus making it ideal for shielded and armoured targets. The bullet was formed of a thin steel shell filled with plastic explosive, with a delayed action base fuze towards the rear. Upon impact with a target the bullet would deform and form a disc or 'pat' of explosive with an increased surface area. A millisecond later the base fuze detonated, creating a shock wave that, owing to its large surface area and direct contact with the target, was transmitted through the material. The round was able to effectively defeat active shields due to primary kinetic, secondary explosive and tertiary kinetic effects. If impacting on armour, the round would cause little damage to the armour itself but directly damage the target through the resulting shockwave. This shockwave was highly disruptive to internal organs, often tearing vital organs from their connective vessels or reducing them to a thick paste. In some cases, the shockwave would cause a secondary effect known as spalling, where minute fragments of the armour's internal layer would be projected off it at high velocity, known as spall. In these cases secondary damage was enhanced by a sort of fragmentation effect inside the target's own body, and caused by their own armour. The round was relatively cheap to produce and was effective against unarmoured, armoured, unshielded or shielded infantry targets.
==Variants==
===M62 Heavy Barrel===
The M62 Heavy Barrel, or M62HB, was identical to the standard variant apart from that it featured a 36 inch (910mm) barrel instead of the usual 872mm (34 inch). This increased its accuracy, range and muzzle velocity markedly, though made the weapon rather large and unwieldy in close quarters combat and other space-restricted tasks. The heavy barrel also helped steady the end of the rifle, reducing muzzle climb when firing on full auto and in rapid bursts. This increased the accuracy and overall effective range of the weapon. As the weapon was made so cumbersome, it was usually issued to designated marksman operating outside of squad-based tactics, rather than for squad-based tactics or as a service rifle.
===M62 Carbine===
The M62 Carbine was a shortened variant, intended for use at closer ranges than the M62. It featured a substantially shortened external barrel, as well as space saving measures and shorter carrying handle and forward handgrip. This reduced the weapon's length by 192mm, making it just 720mm long; its barrel length was reduced from 872mm (34.3 inches) to 680mm (26.7 inches), reducing range and muzzle velocity but making the weapon more easily wielded in tight quarters. It was mainly used by special forces, in particular ODSTs, who needed the firepower the 9.5x60mm round offered but were short on space. It was also on occasion issued to vehicle crews as a defensive weapon alongside more conventional and popular submachine guns.
==Gallery==
Image:BR60-variant2.png|A M62 with an ACGN/D Scope and folding bipod.
Image:BR60-variant3.png|A M62 with M228 CICOG N/D Sight, M157 Suppressor and ALAM II Aiming Module.
Image:BR60-variant.png|A M62 with its carrying handle and cheekrest removed, without iron sights.