Ammunition (AAO)

5x23mm (.20 Caliber)
The 5x23mm caseless is the standard ammunition used in the M7, M12, and M14 SMG series.

Caseless Shield/Armor-Piercing-High Explosive
The S/AP-HE is a prototype round used to expand the versatility of the SMG in close quarters roles against larger targets. Besides having an armor-piercing capability, the round has a coating that allows it to pick up an electrical charge in flight and increase the damage to shields by disrupting the magnetic alignments. Anecdotes from the field claim that several rounds can create a hole in a shield for a split second, allowing another round to pass through while the shields are still active. Tests in the lab have yet to confirm these tales.

7.62x51mm (.30 Caliber)
The 7.62x51mm round is in use in the MA5, MA6, and MA7 series of assault rifles.

7.62x51mm NATO
The standard ammo for the MA7 series was the basic 7.62x51mm NATO round. It was replaced in 2575 by a more effective armor-piercing round.

Incendiary
Not long after the installation of the MA7 series in to active duty came the introduction of incendiary ammunition. While not being able to punch as far in to tissue it has been found to be a highly effective weapon against unshielded targets, especially Unggoy and Flood.

EMP
The EMP round, introduced in 2574, is a revolution in firearms history, putting the ability of an electromagnetic pulse in a relatively small round. The power output is not extreme, but it is enough to rapidly take out a shielded enemy, and it is advised that, if available, every third, fourth, or fifth round be an EMP round.

However, this ammunition is generally only available to Special Forces.

Armor-Piercing
Due to the rising amounts of Covenant in the mid-2570s, an armor-piercing (AP) round was developed for the MA7 series. It is made out of depleted uranium with a tungsten-carbide core.

9.5x40mm (.37 Caliber)
The 9.5x40mm round was a full-power rifle round used with battle rifles, notable the BR55 and BR60 Battle Rifles. The 9.5x40mm KURZ round used a highly experimental chemical propellant (rumoured to be a plasma-based component derived from Covenant technology), meaning the round was able to produce a higher muzzle velocity than the 7.62x51mm NATO round, doing so with a smaller casing and a larger bullet. The round's increased velocity and weight considerably increased its kinetic energy, meaning that upon impact with a target it imparted a significant amount of energy. This, along with its accuracy and range contributed to its potency; it was effective against body armour and even energy shielding employed by Covenant infantry.

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 BR60 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 or 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. Despite its effectiveness against a wide range of target types, it was highly expensive, meaning its cost limited its use. As a result it was normally employed only by special forces operators and select few ODST 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, giving an increase of about a third to the amount the bullet would drain a shield (assuming a distance of 500m). 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 tungsten carbide penetrator 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. The bullet's outer 'shell' was composed of hardened steel, which was webbed with prefragmented lines or weaknesses in the metal; the rear of the core penetrator was similarly fractured, and contained inside it a delayed timer fuze. A short amount of time after hitting a target and penetrating to its innards, the fuze would activate, blowing the penetrator apart along its stress lines, fracturing the external steel jacket and devastating the target's innards with white-hot metal fragments.

M637 Jacketed Hollow Point
M637 Jacketed Hollow Point (JHP)

M638 Tracer
The M638 Tracer

M639 Shield/Armour Piercing
The M639 Shield/Armour Piercing (S/AP)

11.43x23mm (.45 Caliber)
The 11.43x23mm (.45 Caliber) round is primarily used by the Model 2511 Pistol.

Automatic Colt Pistol Hollow-Point Explosive
The 11.43x23mm Automatic Colt Pistol HPE round had the power and explosive potential to penetrate body armor, and explode about halfway through the body, maximizing damage. As a result, a single bullet could kill a Grunt. It could even kill a Brute in half a magazine if each shot was well placed.

Semi-Armor-Piercing High-Explosive
The 12.7x40mm SAP HE rounds of the M6 and SM6 series have carried over in to the SM6D, albeit with superior material purity. It was also used in the SRSS Nyegen 48.

Armor-Piercing High-Explosive
The AP HE round for the SM6 series is made out of experimental polymer composites designed to null the effects of body armor by keeping the force of impact to a small area. This increases the chances of penetration. Upon passing through the armor the round explodes, dealing severe damage to a target.

Magnum
The 12.7mm Magnum round contains an increased amount of propellant for an increase in muzzle velocity and stopping power.

Armor-Piercing
The 12.7x40mm Armor-Piercing round is a full metal jacket tungsten carbide slug with a lead core. The AP round also comes in a magnum variant.

14.7x114mm (.57 Caliber)
The 14.5x114mm is the standard ammunition size for most of the UNSC's anti-materiel snipers and rifles, including the SRS66S-S2, the SRS99D-S3, and the M90909 Javelin. The most popular anti-materiel round used by the UNSC, it is smaller and lighter than larger calibres, maintaining a portable weapons system, while also ensuring high accuracy and stopping power.

Armor-Piercing Fin-Stabilized Discarding-Sabot
The standard APFSDS round is incredibly useful against armored targets at extended ranges, capable of piercing tank armor and killing shielded enemies with one well-placed shot.

Tracer Rounds
The tracer round is a subsonic dart that has the ability to stick to armor. It acts as a GPS tag, allowing a scout to easily track the movements of enemy vehicles. A skilled operator can use it to track the movements of an entire armored block and feed the data to command.

8 Gauge
This is the standard ammunition for most UNSC shotguns.

Buckshot
A standard spray of pellets high on stopping power but low on armor penetration.

Flechette
The 8-gauge flechette round is a deadly close-quarters armor-piercing ammunition that retains the stopping power of the standard buckshot ammunition.

40x53mm
This ammunition type is also referred to as "40 millimeter", due to the thickness of the ammunition type. The 40x53mm grenade is used by most grenade launchers including the MG460 Grenade Machine Gun.

High Explosive (HE)
The standard 40 millimeter projectile. The projectile is filled with high explosive, which is detonated upon impact with an object or the ground.

High Explosive Dual Purpose (HEDP)
The HEDP round is an improved variation of a HEAT warhead that is surrounding with a conventional fragmentation casing to allow the warhead to be more effectively used for blast, and fragmentation attacks on unarmored targets.

Flare
A Flare projectile is a single slug of burning chemicals, appearing in red, green, or white coloring, depending on the. Each projectile casts brilliant light and intense heat without an explosion. These flares are used for signaling, illumination, or defensive countermeasures in military applications.
 * M804F - Red
 * M805F - Green
 * M896F - White

Hyperdense kinetic penetrator
Ammunition type fired by the M68 Asynchronous Linear-Induction Motor. It was designed to cause hypervelocity collisions, where the target and slug get almost entirely vaporized on impact. This was intended to reduce over-penetration, and risk of friendly fire. The ammunition is capable of being shot almost 16 kilometers, at a velocity of mach 40, with near-perfect accuracy.

20x128mm
The 20x128mm was a large calibre anti-materiel round used in some light autocannon, most notably the M3706 Autocannon. The round was deadly against infantry to an exessive degree, often reducing them to unidentifiable chunks as a result of sheer kinetic energy (even without secondary effects). As a result, although it could perform anti-personnel roles more than admirably, the round's primary usage was anti-vehicle and anti-air, where its stopping power and range, often coupled with rate of fire, made it formidable against lightly armoured aircraft and vehicles. A small number of anti-materiel rifles were chambered in the 20x128mm caliber, though the 14.7x114mm round was far more popular in this usage.

M752 High-Powered Semi-Armour-Piercing
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.

M753 Semi-Armour Piercing-High Explosive Incendiary
The M753 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 or 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. Despite its effectiveness against a wide range of target types, it was highly expensive, meaning its cost limited its use. As a result it was normally employed only by special forces operators and select few ODST units.

M754 Shield/Armour Piercing-High Explosive
The M754 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, giving an increase of about a third to the amount the bullet would drain a shield (assuming a distance of 500m). 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 tungsten carbide penetrator 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. The bullet's outer 'shell' was composed of hardened steel, which was webbed with prefragmented lines or weaknesses in the metal; the rear of the core penetrator was similarly fractured, and contained inside it a delayed timer fuze. A short amount of time after hitting a target and penetrating to its innards, the fuze would activate, blowing the penetrator apart along its stress lines, fracturing the external steel jacket and devastating the target's innards with white-hot metal fragments.

M6755 Tracer
The M755 Tracer

155mm HE Shell
The standard 155mm high explosive shell is used for bombarding an area. It is not wholly accurate, but is perfect for destroying clustered formations and suppressing fire.

155mm Cluster Shell
The 155mm cluster shell extends the effective blast area of the standard HE shell. As the shell descends and approaches the ground, a proximity sensor causes the shell to split and spread a dozen warheads over an area.

155mm Guided Munition
The 155mm guided munition is a long-range projectile that is fired in to the air and, once it reaches max height, rotates and fires straight at a marked target. The target is generally marked by a designation laser by frontline troops.

Medusa-II Missile
The Medusa-II was an update of the Great War-era Medusa Missile. 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-II 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 Medusa-II featured both contact and proximity detonation systems, meaning it was more likely to damage a target that was taking evasive action.

Scorpion-IV Missile
The Scorpion-IV Missile is an updated iteration of the earlier Scorpion-II Missile. Operating exclusively as an air-launched ground attack missile, the Scorpion-IV 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 Medusa-II, the missile featured multiple types of both primary and backup target acquisition sensors, enabling it to thwart most active and passive countermeasures.

Longbow-XII Missile
The Longbow-XII Missile was a small antiship missile designed for launch from fighter-sized platforms such as the Longsword. The Longbow featured a comparatively small thermonuclear warhead, although it was encased in a lithium triteride shell, which magnified the blast hundreds of times and gave it strength roughly half that of the much larger Shiva-class Nuclear Missile. The advantage of this was allowing the Longsword to carry munitions capable of more than just denting Covenant vessel's shielding and armour. The Longbow featured advanced guidance and logic systems which enabled it to defeat the vast majority of passive and active countermeasures.

Shiva-class Nuclear Missile
The Shiva-class Nuclear Missile was a starship/starfighter-launched missile with a variable yield thermonuclear warhead, designed primarily for antiship purposes. The power of the weapon was such that a direct hit would disable a fully protected CCS-class Battlecruiser's shields and deal moderate damage to its hull. The Shiva was most commonly deployed from UNSC warships though could also be used by single ships such as the F-352B Longsword-class Starfighter and F/A-361 Scythe-class Interceptor.

Zinko-class Nuclear Missile
The Zinko-class Nuclear Missile was a replacement for the ageing Shiva-class, featuring more advanced stealth, targeting and anti-countermeasure design features, allowing it a far greater chance of reaching its target. The Zinko was most often deployed from UNSC warships though could be launched from ground based facilities also, and larger starfighters could carry it into action if necessary.