Universal Squad Firearm

TCN
TCN in Rifle configuration
Type	Modular weapon system Carbine Assault rifle Light machine gun Squad automatic weapon
Place of origin	Zacapican
Service history
In service	1966 - Present
Used by	Zacapine Armed Forces
Production history
Designer	Yoxen Tzacol NTT 64
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 NTT 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.

Service history

TCN in belt-fed LMG configuration