M105 shotgun

The M105 Shotgun was a recoil-operated, semi-automatic shotgun used by the United Nations Space Command. Reliable and relatively lightweight, the M105 was a powerful close range weapon which was commonly carried by UNSC troops of both the Army and Marine branches, and used to great effect on naturally stronger alien species such as . The M105 was designed by Misriah Armoury solely for military applications, and was the direct successor to the UNSC's venerable .
==Usage==
The M105 found usage in most combat environment that involved close quarters encounters with enemies, predominantly urban and shipboard environments. Its relative small size and extensive stopping power made it an ideal weapon for such combat, and it saw extensive use with Army forces fighting in built-up areas and Marines participating in shipboard action. Effective at room clearing and breaching operations, the M105 Shotgun also saw some usage as a defensive weapon for vehicle crews, though its employment in this role was comparatively limited.
==Design==
The M105 was a lightweight, powerful and modular weapon designed for close quarters combat. It featured attachment rails on the upper and lower body, allowing for additions such as aiming devices and foregrips respectively. Behind the ergonomically designed pistol grip was the detachable stock; fixed and retractable ones were both commonly used though it could be removed altogether if necessary. The M105 was semi-automatic, with the shell chambered using the physical recoil from the shell fired (ejection for the casing was not needed as it utilised caseless shells). Rather than a traditional integral (non-removable) tubular magazine, with each shell loaded manually, the M105 featured a unique detachable magazine which was loaded from the front of the weapon. This magazine was located directly above the barrel and, once in place, functioned as a regular shotgun magazine. The weapon accepted 9-shell magazines, while the compact variant held 5-shell magazines.
==Ammunition==
The M105 Shotgun inherited the 8 Gauge, 3.5 inch magnum shell calibre from its predecessor, the M90 Close Assault Weapon System. The shell was an unsually large calibre for military applications, being considered more powerful than necessary for most uses. It was, however, this aspect of the M90's design that made it so effective against shielded and armoured Covenant at close range; as a result, this was carried over with the M105. The recoil, although substantial, was reduced considerably by absorpsion systems featured into the weapon's design, allowing it to to be properly controlled and wielded effectively. There were various forms of ammunition in the 8 Gauge calibre, with the M1056 Shot and M1059 Incendiary Flechette being most widely used. The M105 utilised caseless ammunition like the majority of the UNSC's small arms; as a result, the weapon did not need to feature an ejection mechanism for the shell's casing after firing.
* 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.