Universal Squad Firearm
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| TCN | |
|---|---|
 TCN in Rifle configuration | |
| Type | Modular weapon system |
| Place of origin |  Zacapican |
| Service history | |
| In service | 1966 - Present |
| Used by | Zacapine Armed Forces |
| Production history | |
| Designer | Yoxen Tzacol YAT 25 |
| Designed | 1966 |
| Manufacturer | Cuauhquetztia |
| Produced | 1966 - Present |
| No. built | Approx. 4 million |
| Specifications | |
| Weight | LMG: 11.68 lb (5.30 kg) FMG: 10.31 lb (4.68 kg) Carbine: 7.90 lb (3.58 kg) Rifle: 7.75 lb (3.52 kg) |
| Length | LMG, Rifle: 40.25 in (1,022 mm) Carbine: 36.68 in (931.7 mm) stock extended / 26.60 in (675.6 mm) stock collapsed FMG: 30.38 in (771.7 mm) |
| Barrel length | LMG, FMG, Rifle: 20 in (508.0 mm) Carbine: 15.7 in (398.8 mm) |
| Cartridge | 7.65×33mm Ahuatetz 7.65x53mm Hueiyac |
| Action | Gas-operated rotating bolt system |
| Rate of fire | LMG, FMG: 700–1,000 rounds/min Rifle, Carbine: 700–900 rounds/min |
| Muzzle velocity | LMG, FMG, Rifle: 3,250 ft/s (991 m/s) Carbine: 3,050 ft/s (929.6 m/s) |
| Effective firing range | 200–1,000 m |
| Maximum firing range | 2,650 m |
| Feed system | LMG, FMG: Disintegrating ammunition belt Rifle, Carbine: 20- or 30-round detachable box magazine LMG: 75-, 100-, 150-round drum magazine |
| Sights | Iron sights |
The Universal Squad Firearm (𐐓𐑊𐐯𐐿𐐨𐐿𐐨𐑆𐐻𐑊𐐨 𐐝𐐯𐑌𐐻𐐯𐐿𐐭𐐸𐐻𐑊𐐨 𐐤𐐬𐐸𐐶𐐨𐐷𐐰𐑌𐐷𐐬, Tlequiquiztli Centecuhtli Nohuiyanyo, TCN) is a modular weapon system capable of being configured as an automatic rifle, a carbine, and a light machine gun or squad automatic weapon. It can also serve as a vehicle mounted weapon. This gives the weapon system its name, as its design allows the same central firearm components to be used in every weapon employed by a typical infantry squad. It is the main service weapon of the Zacapine Armed Forces in the assault rifle, carbine, and light machine gun roles. The rifle and carbine configurations fire the intermediate 7.65×33mm Ahuatetz "short" cartridge, while the machine gun configurations use the 7.65x53mm Hueiyac "long" rifle cartridge. An export version of the system, the Octacatl Nanauhtetl Tepozmatatl (Four-system Bullet-caster) weapon system, is chambered in the non-proprietary 7.62x51mm.
The purpose of the level of modularity seen in the TCN system was to greatly reduce the long term manufacturing and maintenance costs that came from outfitting nearly the entire Zacapine military with a single family of firearms, as most parts would be entirely interchangeable across the infantry weapons which various configurations of the TCN could become. This logistical consideration was the primary motive behind the initiative to design and produce the TCN system. Converting TCN weapons from one configuration to another in the field was never seriously considered as a design objective and would never be implemented, with a particular configurations being assembled in the factory or in the military armories. A sniper rifle version of the TCN was considered but ultimately rejected due to the unique design requirements for such a high precision, low rate-of-fire type of firearm interfering with the needs of the other configurations of the TCN, as well as the relatively small number of sniper rifles needed by the military.
Development
The idea for an all-in-one weapon system saw its beginnings in the Hanaki War, when Zacapine forces were first introduced to the sub-machine gun concept. Zacapine Army command had long rejected the concept and derided such weapons as "gangster guns", a notion which was challenged by the experiences of the war. Designs for new sub-machine guns were requested from the YAT design units involved in small arms design starting in 1929, a few years after the war, during which one proposal later known as the Tzimitl Prototype was produced. The Tzimitl system was among the earliest designs considered to be within the category of an assault rifle, while the system was proposed as a sub-machine gun hybridized with a rifle, which could replace both the bolt action rifles and light machine guns of the era. The prototype would ultimately be rejected due to the high weight, low reliability and heavy recoil of the rifle caliber cartridges the Tzimitl was chambered in, but it had established the principle of filling several combat niches with a single system. It would be this failed prototype that would be the inspiration for the TCN project.
The TCN was a proposal of Yoxen Tzacol, a respected Jewish Zacapitec small arms designer assigned to the Andras design bureau (YAT 25).
Cartridge
The different configurations of the TCN, because of their differing roles, create different considerations when it comes to ammunition. As a Rifle and a Carbine, the TCN would function best with a lighter intermediate cartridge. Such a cartridge could offer better precession than would be necessary in the machine gun configuration, and would also lessen the recoil. Both of these factors would increase the practical accuracy and therefore the combat effectiveness of the these configurations of the TCN. Conversely, such a light and underpowered cartridge would reduce the effectiveness of the infantry portable as well as the vehicle mounted machine gun configurations, particularly harming its effectiveness in an anti-vehicle and anti-aircraft role. For these configurations, a heavier cartridge with greater penetration characteristics would be preferred. These diverging considerations resulted in the addition of a two-cartridge design with a barrel sized for bullets 7.65mm in diameter. The chamber is sized by default for 7.65x53mm cartridges, the long Hueiyac rounds with the high pressure load used by the machine gun TCN. A spacer is then added to convert the weapon to 7.65x33mm, the Ahuatetz intermediate cartridge used in the rifle and carbine configurations.
