UNSC Ammunition

The United Nations Space Command utilised a large and diverse range of munition and ordnance types in its role as military branch of the Unified Earth Government. This range of armaments allowed it to more effectively combat threats to Humanity such as the and Covenant Remnant. The UNSC seemed to be perpetually at war during the late 25th, 26th and 27th centuries; firstly fighting Human separatists, then the Human-Covenant War between 2525 and 2552 and subsequent Remnant War.
In the post-Human-Covenant War period, the UNSC also benefited from vast technological knowledge obtained from its new allies, the advanced Sangheili, Huragok and reverse-engineered Forerunner technology. The culmination of this, as well as the UNSC's near-ceaseless warring, was an increasingly advanced, effective, vast and ever-changing range of deadly armaments developed for combat. Far from solely ballistic weaponry and guided missiles, though these consisted of the staple ordnance, the UNSC also operated a large number of guided and unguided bombs, rockets, grenades, and kinetic projectiles such as solid slugs for magnetic accelerator cannons and railguns.
==Propellant==
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 , 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 UNSC's caseless ammunition maintained a tolerance similar to traditional, cased bullets. This was acheived 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 to noticeably increased damage dealt to the target in terms of kinetic effects; this also markedly improved its armour and shield penetration characteristics. Muzzle velocities were typically two to three times higher with caseless ammunition than traditional cased types; 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 weapons' internal mechanisms, as there was no need for extraction and ejection of spent casings. As overall round was smaller, it allowed for larger magazines, and its significantly reduced weight increased the amount of ammunition a soldier could realistically carry.
The 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 , 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.
==Pistol Ammunition==
===12.7x40mm===
===9.4x26mm===
==Small Calibre Rifle Ammunition==
===5.2x47mm Hall===
M8 submachine gun
MP8 personal defence weapon system.
===7.62x51mm NATO===
The 7.62x51mm NATO round was the most commonly used round in service with the UNSC, being adapted from the MA5 series of Assault rifles, and used in the MA6 and MA7 series as well as light machine guns. The round gave a near perfect balance of range, stopping power, accuracy and recoil, making it ideal for use in infantry weapons such as the MA6 assault rifle and the M62 light machine gun. The round consisted of a 7.62mm bullet embedded in a block of solid chemical propellant; this sat between a combustible primer and a disintegrating cap, which held the bullet in place.
====M601 Semi-Armour Piercing-High Explosive Incendiary====
The M601 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.
====M602 Shield/Armour Piercing-High Explosive====
The M602 Shield/Armour Piercing-High Explosive, also known as S/AP-HE, was the most common and effective type of ammunition employed in the 7.62x51mm 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.
====M603 Jacketed Hollow Point====
M603 Jacketed Hollow Point (JHP) round was a specialised munition for unarmoured and lightly armoured infantry, being at its most effective when utilised against Kig-Yar and Unggoy.
====M604 Tracer====
The M604 Tracer
====M605 Armour Piercing High Explosive====
The M605 Armour Piercing High Explosive round (AP-HE) 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.
====M606 High Explosive Squash Head====
The M606 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.
===9.5x60mm===
The 9.5x60mm round was an intermediate calibre, high power rifle round initially developed for the BR55 battle rifle as the 9.5x40mm KURZ (or Short). While typically producing more recoil than smaller calibres, it achieved increased stopping power and muzzle velocity which resulted in its increased lethality. The round was designed by Misriah in the 2540s and was a caseless evolution of the conventional 9.5x40mm KURZ cartridge, and was designed for use in the M73 machine gun before being adopted by other weapons. The round was utilised in battle rifles such as the M62 battle rifle and M18 battle rifle, and also general purpose machine guns like the M73 machine gun. The round typically produced good range and accuracy, making it ideal for squad marksman duties and highly accurate mid to mid-long range combat. The round consisted of a 9.5mm bullet embedded in a block of solid chemical propellant; this sat between a combustible primer and a disintegrating cap, which held the bullet in place. 
========
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 millisecond 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====
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.
==Large Calibre Rifle Ammunition==
===10.2x74mm===
The 10.2x74mm calibre was an anti-personnel round mainly reserved for some lighter sniper rifles, such as the M45A sniper rifle. The round was an intermediary between smaller, less powerful rifle rounds such as the 9.5x60mm and larger, more unwieldy anti-matériel rounds such as the 14.5x11mm round. As a result of this, it maintained accuracy, stopping power and recoil best suiting it for designated marksman, anti-personnel duties and other 'lighter' long range roles. At 4000m, and disregarding secondary damage from explosive or deforming, the round had a kinetic energy on target of 315.5 kilojuoules. This is based on a muzzle velocity of 3,500m/s.
===12.7x99mm===
The 12.7x99mm round (also known as the .50 BMG) was a large calibre round utilised in an anti-matériel role, predominantly by sniper rifles and heavy machine guns.
===14.5x114mm===
The 14.5x114mm round was a heavy calibre round used for heavy machine guns and anti-matériel rifles. It had massive stopping power and penetration, but was impractical for use in smaller infantry weapons without considerable recoil. It had good range and armour piercing characteristics but was largely limited from small arms usage.
==Shotgun Ammunition==
Designed and utilised predominantly for close range combat, shotguns formed a small though essential, part of the UNSC arsenal. Especially used by special forces, Marines and close quarters troops, they were most effective at shorter ranges, and had stopping power capable of taking down even the heaviest infantry units at optimum ranges. Their ammunition types were diverse and varied, providing a tailored response to each situation.
===8 Gauge===
The '8 Gauge' shell was a powerful shotgun shell which provided extreme stopping power at close range. It was a relatively large calibre shotgun shell, most notably used by the M105 shotgun. It had large stopping power at close and short-medium ranges, and was popular among combat troops. The shell's length was 3.5 inches, giving it metric dimensions of 21.21x88.9mm.
====M1056 Shot====
Alongside the M1059 Incendiary Flechette, the M1056 Shot Shell was the standard shell issued in the 8 Gauge calibre. The shell itself contained either 50 smaller or 20 larger spheres of CVT (Chromium Vanadium Tungsten) and Austenitic Steel alloy. Though actual spread varied according to the weapon itself, the shell generally possessed good range qualities. This was coupled with high stopping power, shield depleting and armour piercing characteristics, which meant that a single discharge could usually overcome all but the strongest adversary within its optimum range.
====M1057 Sabot====
The M1057 Sabot shell was a specially shaped, two-stage cartridge. It had an outer jacket that enabled it to travel further, outside a standard shot of 40 small spheres of CVT/Steel alloy, or alternately 15 larger ones. The shell had a long range but relatively low penetration.
====M1058 Flechette====
M1058 Flechettes were similar to the M1057 Sabot, though replaced the shot with hundreds of CVT/Steel alloy subprojectile barbs or flechettes. These had high range and were usually deadly to armoured targets. The M1058 was in most respects superceded by the M1059.
====M1059 Incendiary Flechette====
The M1059 contained roughly 60 small, fin-stabilised armour piercing flechettes. These flechettes were composed of the 'TC3' alloy (made up of tungsten, cerium and copper carbide), and had indendiary, self-sharpening and pyrophoric properties similar to uranium without associated radiological effects. The flechettes had powerful armour-piercing ability and secondary incendiary effects to do high damage after initial contact with a target.
====M1060 Explosive Shot====
The M1060 Explosive Shot Shell was a standard shell filled with approximately 30 small explosive projectiles, utilising a powerful plasma-based explosive. Penetration was low, but actual power was high, especially against shielded targets; this resulted in their use being mainly tailored towards shielded enemies.
====M1061 Slug====
The M1061 Slug was essentially a crude rifle round, using a rifled, hollow slug consisting of a lightweight deforming ballistic cap and a CVT/Alloy exterior. Subtypes of this round include the M1061A Explosive Slug, which saw the hollow interior filled with a plasma-based explosive, the M1061B Armour Piercing Slug, which contained a TC3 alloy penetrator, and the M1061C Incendiary Slug, the interior of which was filled with an incendiary material.
===12 Gauge===
Smaller than the 8 Gauge shell, the 12 Gauge was slightly less powerful than but was smaller, which allowed greater numbers to be carried and used against the enemy. The M42 Close Assault Weapon System, an automatic shotgun, utilised this round, as did the M11 Tactical Shotgun.
====M1071 Shot====
Alongside the M1074 Incendiary Flechette, the M1071 Shot Shell was the standard shell issued in the 12 Gauge calibre. The shell itself contained either 50 smaller or 20 larger spheres of CVT (Chromium Vanadium Tungsten) and Austenitic Steel alloy. Though actual spread varied according to the weapon itself, the shell generally possessed good range qualities. This was coupled with high stopping power, shield depleting and armour piercing characteristics, which meant that a single discharge could usually overcome all but the strongest adversary within its optimum range.
====M1072 Sabot====
The M1072 Sabot shell was a specially shaped, two-stage cartridge. It had an outer jacket that enabled it to travel further, outside a standard shot of 40 small spheres of molecularly compressed CVT/Steel alloy, or alternately 15 larger ones. The shell had a long range but relatively low penetration.
====M1073 Flechette====
M1073 Flechettes were similar to the M1072 Sabot, though replaced the shot with hundreds of CVT/Steel alloy subprojectile barbs or flechettes. These had high range and were usually deadly to armoured targets. The M1073 was in most respects superseded by the M1074.
====M1074 Incendiary Flechette====
The M1074 contained roughly 60 small, fin-stabilised armour piercing flechettes. These flechettes were composed of the 'TC3' alloy (made up of tungsten, cerium and copper carbide), and had incendiary, self-sharpening and pyrophoric properties similar to uranium without associated radiological effects. The flechettes had powerful armour-piercing ability and secondary incendiary effects to do high damage after initial contact with a target.
====M1075 Explosive Shot====
The M1075 Explosive Shot Shell was a standard shell filled with approximately 30 small explosive projectiles, utilising a powerful plasma-based explosive. Penetration was low, but actual power was high, especially against shielded targets; this resulted in their use being mainly tailored towards shielded enemies.
====M1076 Slug====
The M1076 Slug was essentially a crude rifle round, using a rifled, hollow slug consisting of a lightweight deforming ballistic cap and a CVT/Alloy exterior. Subtypes of this round include the M1076A Explosive Slug, which saw the hollow interior filled with a plasma-based explosive, the M1076B Armour Piercing Slug, which contained a TC3 alloy penetrator, and the M1076C Incendiary Slug, the interior of which was filled with an incendiary material.
==Shell Ammunition==
===20x128mm===
===30mm===
===65mm===
===82mm===
===105mm===
===120mm===
===Ammunition Types===
==Grenade Ammunition==
==Missiles and rockets==
===FGM-91 Razor===
===AGM-148 Scorpion===
The AGM-148 Scorpion was an air-to-ground anti-armour and anti-structure missile and the replacement for the Great War-era . The AGM-148 was a hypervelocity contact/proximity detonated missile; although lacking in agility, its speed and high accuracy virtually guaranteed a direct hit against slow and medium moving ground vehicles and stationary structures. Using the same tandem HEAT/kinetic energy penetrator warhead as the AIM-109 Medusa, the missile featured multiple types of both primary and backup target acquisition sensors, enabling it to thwart most active and passive countermeasures.
The missile was used by the F/A-352B Longsword multirole strike craft through use of internal hardpoint bays, though could also be utilised by the mounted to its wing hardpoints. The missile was utilised exclusively against ground craft, and saw extensive employment by air support VTOL craft for anti-armour and anti-structure fire.
The Scorpion was a fire-and-forget, multi sensor-guided air to ground missile. It featured combined RADAR, UV and optical guidance systems to best ensure a direct hit to the target, and prevent being interfered with by enemy countermeasures. Internally, the missile made use of several combined antitank methods to ensure the best possible rate of target destruction. It also featured various rudimentary computing systems, which enabled it to overcome both passive and active countermeasures in favour of the real target. The missile's payload was arranged as a tandem HEAT warhead with a kinetic energy penetrator in between the two. The first explosion would severely damage the external target's armour and defeat any present reactive armour or shielding. A splitsecond later, the larger, second lot of explosives would detonate, channeling the most of its power forward, damaging the armour again but also sending a kinetic energy penetrator at superhigh velocity into the target's armour. This penetrator was made up of a laminated tungsten alloy, comprised of tungsten, cerium and copper carbide (altogether known as TC3). This had self-sharpening, pyrophoric properties, virtually guaranteeing a kill against even the most advanced strongest shielding and armour. Its self-sharpening properties meant that upon hitting enemy armour, the penetrator's tip would fragment in a way so that the remaining tip still remained sharp. Its pyrophoric properties gave it a useful secondary explosive/incendiary property, gutting enemy vehicles and killing their crew. When engaging infantry, more lightly armoured targets or large, unarmoured structures, the tandem warhead would instead detonate simultaneously, creating a more powerful explosion and making it overall more effective. The missile's target tracking arrays and simple propulsion systems were located at the rear of the missile. It was not an agile missile and was unable to engage any targets other than immobile, slow or medium-speed targets at ground level.
===ASR-62 Thor===
The ASR-62 Thor was a 90 millimetre air-launched unguided rocket designed for general use against ground targets such as infantry and armoured vehicles. The Thor featured a WAFAR wrap-around fin aerial rocket) design which enabled it to be hot-launched from rocket launchers, most notably the M691 rocket launcher. The Thor was used by vehicles engaging in air-to-ground combat and close air support, such as the MV-14B Hornet, though could also be fitted to fighter craft, such as the F/A-352B Longsword strike fighter. The Thor was compatible with a range of warheads including high explosive, submunition and flechette warheads.
===AIM-109 Medusa===
The AIM-109 Medusa was a small, trans-atmospheric capable, ship-to-ship (or air-to-air in atmosphere) guided missile, designed to replace the Great War-era . Designed for launch from small mobile platforms such as starfighters, it was most effective against Covenant single ships such as the Seraph-class starfighter, being capable on most occasions of destroying it with either a direct hit or a close proximity detonation. The Medusa featured several homing systems to prevent it being jammed by enemy countermeasures, and an advanced HEAT tandem warhead with kinetic energy penetrator. This was most effective at destroying targets with a direct hit but could heavily damage them even with a near miss. The AIM-109 featured both contact and proximity detonation systems, meaning it was more likely to damage a target that was taking evasive action.
===RIM-109 Medusa===
The RIM-109 Medusa was a larger variant of the AIM-109, designed for launch from warships rather than starfighters. Designed for long range, defensive capabilities in a predominantly point-defence role, but with an offensive ability also, the Medusa was carried by UNSC starships of corvette tonnage and above, and was mainly stored and launched from multi-cell block-like silos, allowing large numbers of missiles to be carried. The RIM-109 was designed specifically to intercept starfighters and incoming missiles, and was small especially in comparison to other shipboard missiles such as the Archer and Harpoon. This specialisation allowed the Medusa to easily close with and destroy missiles and single ships, being designed to maximise the likelihood of a one-hit kill against Covenant starfighters such as the Seraph. The RIM-109 was produced in two variants, each sharing the same warhead, guidance and launch systems. The RIM-109A was the heavier, larger variant, possessing better acceleration (and therefore increased spatial range) and designed for fleet air defence, and equipped on destroyers and cruisers. The RIM-109B was a lighter, smaller missile, with a smaller below-deck presence, making it suitable for smaller vessels such as frigates and corvettes, and larger vessels such as carriers and assault ships. The 109B was employed in a self defence role, having approximately half the acceleration and useful range of the larger 109A. The Medusa was first developed for use on the Vengeance-class destroyer, which served from 2544 onwards, as one of many new technologies this class combined. It was later refitted to selected ships of the Marathon- and Halcyon-class cruisers throughout the 2550s, as a stopgap measure until megnetic acceleration-based area defence weapons matured, and to the Remembrance-class frigate as part of its 2561 refit, once the smaller B variant had been developed.
The Medusa tracked and homed in on its target using a variety of mechanisms. Semi-active RADAR allowed the launching ship to 'illuminate' the target for the missile, allowing it to remain undetected; though it also possessed its own active phased array radar to guide itself if necessary. It also featured a rudimentary ultraviolet, infrared and optical guidance package which enabled it to build up a more detailed picture of the target on final approach, helping to foil passive or active countermeasures deployed against it. The missile featured control surfaces as well as a low-profile cooled vectored-thrust rocket engine, which allowed it to operate in both atmospheric and vacuum environments and remain nimble in both. In spatial use, the missile would shut off its engine once it had reached sufficient velocity, in order to reduce its thermal signature and conserve fuel, propelling itself under inertia and extending its range.
The missile's warhead was essentially an advanced shaped charge, designed to defeat shielding if present and spread destructive power over a wider area than a shaped charge warhead normally would, increasing the likelihood of a strike. The warhead's casing was a lightweight ballistic cap, designed to increase aerodynamic performance and also disintegrate on impact, without hindering the explosive mechanism's effects. Behind this was an cavity formed by the inside of the cap and the shaped charge, which was coating with a liner of the incendiary, dense and ductile 'TC3' alloy, composed of tungsten, cerium and copper carbide. Behind the main shaped charge was the detonator, which was activated either by contact or by proximity with the target. Upon detonation, the shaped charge would form the TC3 into six separate 'long-rod' explosively formed penetrators, which would be ejected forward flechette-like at a velocity of 10 kilometres per second. These penetrators were enough to deplete shields and penetrate armour of the most heavily protected starfighters; however, the greater number of penetrators sacrificed beyond-armour effect against larger targets for increased spread lethality, which was of higher importance for an anti-starfighter and anti-missile weapon. As a result, the Medusa's performance against heavily shielded and armoured targets, such as warships, was comparatively poor.
The explosive shaped charge, which formed the penetrators and gave them their velocity, was HNIW, also known as CL-20, which was a nitroamine explosive which doubled as the missile's propellant through a deceptively simple mechanism. Upon impact with the target, any remaining rocket fuel would simply add to the shaped charge's power, increasing the overall yield and the velocity of the penetrators. The charge and the rocket fuel were separated by simple valves which meant that while it was possible for the shaped charge to use the rocket's unconsumed propellant in its detonation, it was not possible for the rocket to consume the shaped charge after depleting its own supply.
While the beyond-armour effects for each penetrator were less than if it were a single large one, the damaging effects of even a single penetrator were more than sufficient to destroy most starfighter targets; this led to the use of several spreading penetrators rather than a single larger one. The TC3 penetrator was firstly incendiary, meaning it would ignite during initial detonation and then penetrate the armour at high velocity and alight. The high temperature and high velocity armour and penetrator fragments being injected into the interior space, and the blast overpressure caused by this debris, meant the interior of the craft was quickly destroyed beyond recognition. Secondary incendiary effects from the slug and in many cases spalling would add to this destruction. Other warheads such as conventional or annular blast fragmentation, tandem HEAT charge or dual electromagnetic pulse and fragmentation were available, though not as common as the shaped charge warhead.
===AGM-155 Spear===
The AGM-155 Spear was a multi-purpose air-to-ground missile designed for use against generic light targets such as light vehicles, infantry, unfortified buildings and other enemy materiél. The Spear was chiefly launched from a range of aircraft including the MV-14B Hornet, F/A-352B Longsword and F-371 Halberd, though could also be launched from warships in orbit equipped for fire support missions. The Spear guided itself to the designated target through an active phased array radar, and was also equipped with ultraviolet, infrared and optical guidance systems which enabled it to foil passive or active countermeasures deployed against it. The missile's target could be 'painted' from either an air- or ground-based target, allowing units to quickly call in fire support when collateral damage was a consideration (the RSGM-16 Archer was also commonplace in fire support missiles but had a significantly higher yield). The missile featured control surfaces as well as a low-profile cooled vectored-thrust rocket engine, which allowed it to operate in both atmospheric and vacuum environments. The most common warhead fitted to the Spear was a simple high explosive payload, enabling it effective use against a range of targets; though thermobaric and other warheads could be fitted for specific functions.
===BGM-14 Volley===
The BGM-14 Volley was a multirole guided missile designed for launch from a wide range of platforms including ground-based launchers and airborne starfighters. The BGM-14 was designed (as its multirole designation suggested) to be effective against a wide range of targets including both soft and hard ground targets and aerial threats. The missile could be utilised as a MITV, or multiple independently targetable vehicle, when deployed alongside the AM-42 Multiple Ordnance Deployment Missile.
The BGM-14 missile was a small, agile, short range missile, that was designated multi-role reflecting its ability to engage multiple types of target. The missile's warhead was arranged as a tandem HEAT charge with a kinetic energy penetrator in between the two. The first explosion would severely damage the external target's armour and defeat any present reactive armour or shielding. A split second later, the larger, second lot of explosives would detonate, channeling the most of its power forward, damaging the armour again but also sending a kinetic energy penetrator at super high velocity into the target's armour. This penetrator was made up of a laminated tungsten alloy, comprised of tungsten, cerium and copper carbide (altogether known as TC3). This had self-sharpening, pyrophoric properties, virtually guaranteeing a kill against even the most advanced strongest shielding and armour. Its self-sharpening properties meant that upon hitting enemy armour, the penetrator's tip would fragment in a way so that the remaining tip still remained sharp. Its pyrophoric properties gave it a useful secondary explosive/incendiary property, gutting enemy vehicles and killing their crew. When engaging infantry, more lightly armoured targets or large, unarmoured structures, the tandem warhead would instead detonate simultaneously, creating a more powerful explosion and making it overall more effective. This setup made the warhead effective against nearly all targets it could encounter, though alternative types were available for specific mission requirements. The missile's target tracking arrays and simple propulsion systems were located at the rear of the missile.
The Volley could be launched from ground-based launchers or from the hardpoints of aircraft, but its most famous use was with the AM-42 Multiple Ordnance Deployment Missile. The AM-42 ODM would contain within it four Volley missiles. The AM-42 would get within range of the target, then deploy the BGM-14s, preserving their fuel reserves and maximising range. The four sub-munitions would then simultaneously attack the same target, or else attack four separate ones, depending on targeting information supplied to the missile. After the parent missile deployed the Volleys it released a parachute, providing its own continued targeting telemetry to the smaller missiles, which featured only rudimentary tracking systems themselves. The Volley missiles continued to be fed targeting data from other UNSC sources, including the launching craft, these were not likely to be in range and so the now-useless parent missile acted in support. The AM-42, although large and not particularly agile, was capable of hypersonic speeds, had excellent range and endurance and was equipped with better than average sensory equipment. This enabled it to get the BGM-14s in range of their target while preserving their limited fuel, and also then providing telemetry support from afar.
The Volley was effective against most targets, being powerful enough to, when attacking in concert, destroy a Seraph-class Starfighter. The missiles were also extremely agile and capable of hypersonic speed (although their range was limited following separation) and could easily destroy a Banshee with a single impact. The BGM-14 was also highly effective against infantry and light vehicles, and could on individually defeat most of the Covenant's ground vehicles. More armoured targets such as and their successors, the Gun Wraith, could not generally endure two direct hits.
===AM-42 Multiple Ordnance Deployment Missile===
The AM-42 Multiple Ordnance Deployment Missile was a hypersonic guided missile that could deploy multiple types of ordnance; developed to carry the AGM-155 Spear, the AM-42 was also equipped with the BGM-14 Volley as an MITV (Multiple Independently Targetable Vehicle) payload. The AM-42 had a length of four metres and was 1.15m in height; it could store four Volley missiles in helical formation and variable amounts of other munitions. The missile was guided to its target by dual jam-resistant RADAR and infrared/laser guidance. Once detached from the launching craft it was entirely autonomous, and featured various systems to thwart enemy countermeasures.
===ASGM-12 Longbow===
The ASGM-12 Longbow was a small, high yield nuclear antiship missile designed for launch from fighter-sized platforms such as the F/A-252B Longsword. The Longbow was an improved version of the Great War-era antiship missile, featuring improved targeting sensors to maximise its effectiveness against Covenant warships. The Longbow's warhead remained unchanged from its predecessor, being a single thermonuclear warhead with a lithium triteride casing; this casing both focused the blast inwards and added fissionable material to the reaction, resulting in its strength being multiplied a hundred fold from a relatively small initial yield warhead. The advantage of this was the power relative to the missile's size, as it achieved a yield approximate to half that of the highest strength in a fraction of the size, allowing a viable antiship weapon to be carried by fighter-sized craft.
===BSGM-14 Harpoon===
The BSGM-14 Harpoon was a long range, ship-to-ship/ground nuclear missile carried by UNSC warships as a lighter, more variable nuclear option when compared to the RSM-19 Shiva. The Harpoon was first designed for use by the Remembrance-class frigate, but this was soon expanded to destroyers, cruisers and larger vessels. The missile was introduced in 2531, and went through dozens of changes over the decades to ensure it remained modern and fully effective. These missiles were most commonly fired from launch tubes facing the ship's dorsal surface, but a number of ship classes mounted these tubes en masse, allowing them to carry great numbers of Harpoons. These missiles could be fitted with a single large warhead or alternatively, a MIRV warhead, which equipped the missile with multiple warheads that could be independently targeted. This increase in volume of fire partially negated the effect of point defence fire and increased the likelihood that part of the payload would reach the target. The Harpoon missile could be fitted with up to twelve independently targetable warheads with a maximum individual yield of five megatons, giving a maximum overall yield in MIRV configuration of 60 megatons. Higher overall yields of up to 120 megatons were possible using single large warheads, which increased individual power but decreased the likelihood of striking the target. These tubes carried a single missile ready for firing at a moment's notice in the twelve tubes, with a magazine containing additional missiles located adjacent to the tube. The number of additional missiles varied between ships, with the Remembrance- and Daring-class frigates holding one, Vanguard- and Warrior-class destroyers holding two and larger vessels up to five. Reloading these tubes after firing took approximately sixteen seconds. The Harpoon could be equipped with a conventional high explosive or shaped warhead if required. Its designation, BSGM, denoted that its primary launching platform was a variable; the Harpoon was commonly fired from both warship- and ground-based silos. In addition, it was capable of striking both spatial and ground-based targets.
The Harpoon missile went through several iterations during its use. The BSGM-14 Harpoon Mark 6 was used from 2550 onwards and made use of several features to increase its effectiveness. Stealth measures included a shape designed to reduce RADAR cross section, RADAR absorbant materials, and a low detectability hybrid rocket engine, which combined with minimal radio and thermal emissions to avoid detection until the last seconds before impact. As well as this, the Harpoon carried an independent RADAR, ultraviolet, infrared and optical guidance package in case contact between the controlling vessel and the missile was broken. Finally, the missile was equipped with sophisticated systems to avoid and defeat countermeasures deployed against it.
===RSGM-16 Archer===
From the 2560s onwards, with the widespread adoption of turret-mounted MACs and raiguns and the increased lethality of individual Archers, complements of RSGM-16s missiles onboard warships were reduced through modification of their magazines. This reduced weight and increased onboard space for other systems and crew habitation, as well as reducing the amount of explosive ordnance carried. This was in stark contrast to the height of their usage, during the Great War, where capital ships would carry banks of thousands of Archers to compensate for their relative ineffectualness.
===RSM-19 Shiva===
ship-launched, space target, guided missile
==Bombs and gravity-propelled munitions==
===GBU-54 guided flechette===
Although not technically a bomb, the GBU-54 guided flechette was a guided munition that gained propulsion from gravity, rather than an internal system. GBU-54 was a large fin-stabilised metal projectile, featuring satellite, infrared and optical guidance systems and a penetrating tip. The flechette was designed for launch from high altitude or low orbit aircraft, where it would fall to the ground, guiding itself down onto its target and gaining huge kinetic energy in freefall. The flechette was designed against hardened targets such as the heaviest of armoured vehicles and hardened fortifications, and could also be used to great effect against targets of strategic importance. The GBU-54 featured folding wings and fins which saved space when not in use.
Used against hard targets such as armoured vehicles, hardened structures and tactically important sites such as refuelling points, the flechette was launched from a craft often far removed from the target area. This allowed UNSC forces to hit an enemy remotely with precision and power, the flechette being powerful enough to pass right through the top of a main battle tank and then emerge underneath it, impaling it right through, or passing through dozens of floors of a building (or decks of an unshielded ship) before coming to a stop.
The GBU-54 was a flechette designed to be dropped from considerably altitude by air or spacecraft. Featuring self-guidance systems similar to those of a guided bomb, the flechette would guide itself down to its target using predetermined information fed from a wide range of UNSC sources, including ground forces and the launching craft, directly or relayed through satellites. While in freefall, the flechette would make use of control surfaces to adjust its trajectory, ensuring it hit its target. With a mass of 530kg and a total cross-sectional area of less than 80 square centimetres, the GBU-54 had a terminal velocity of 7,636 kph (Mach 6.2) assuming gravity of 1 g. While it did not always reach terminal velocity, depending on the altitude from which it was deployed, its speed was sufficient in any case to critically damage most targets. The flechette contained two main 'wings' and a tail of four stabilising fins, which both stabilised the flechette in freefall and controlled its trajectory. As a space-saving measure, the main wings folded into the side of the flechette and the fins folded sideways, unfolding once it was deployed. The GBU-54's penetrating tip was depleted uranium, featuring a self-sharpening tip. This meant that when the tip fragmented on impact it would do so in a way that the remaining tip was still sharp. DU was also pyrophoric, meaning it had a secondary incendiary effect upon impact, doing considerable secondary damage to the target. Titanium carbide tips were available for usage where collateral damage needed to be kept to a minimum, and various others were available depending on the target/task. A deployed flechette had a length of 2.4 metres and a width of 1.49 metres; while a folded flechette measured 1.9 metres long and 0.61 metres wide.
==Rockets==
==Mines==