UNSC Ammunition

While the United Nations Space Command increasingly relied on directed energy weapons such as Particle Cannons for their main weapon types, ballistic weaponry taking the form of bullets, shells and other projectiles still accounted for a significant portion of UNSC weaponry. Particularly during the Swarm War, ballistic small arms and vehicle weapons remained popular and effective for their stark ability to penetrate The Swarm's natural exoskeleton, in contrast to energy weapons.

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 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 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 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.

5.2x47mm Hall
M8 Submachine Gun

MP8 Personal Defence Weapon System.

6.8x40mm
The 6.8x40mm round was a small calibre rifle round used in assault rifles and carbines such as the M40 Individual Combat Weapon System. Designed as a lighter alternative to the 7.62x51mm NATO round for use in assault rifles and light machine guns, the 6.8mm round boasted an increased rate of fire, better handling characteristics and increased ammunition capacity as benefits, though suffered from decreased range and stopping power when compared to its larger counterpart. Due to its caseless nature, however, combined with its small bullet relative to the amount of propellant, the 6.8mm round benefited from higher muzzle velocities than would normally be achieved, giving it strong ballistic and terminal characteristics for its size.

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 MA7B Individual Combat Weapon System and the M620 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 utilised in battle rifles such as the BR62 Battle Rifle and M18 Battle Rifle, and also saw use with medium calibre machine guns. 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.

M634 High-Powered Semi-Armour-Piercing
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 BR62 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.

10.2x74mm
The 10.2x74mm calibre was an anti-personnel round mainly reserved for some lighter sniper rifles, such as the M45A Compact Ranged Weapon System. 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.