Short haired sister of 74. Even has shorter tail.
In 1973, a design competition codenamed "Modern"—Модерн) was started for the adoption of a fully automatic carbine. Because of combat research from Vietnam, the Soviets never had a carbine.
The AK-74U was a ak-74 variant served for vehicle crews. However Russian special forces like the rifle because it is compact But preferred the AKS-74U because it was lighter with skeleton folding stock and no drawbacks. Eventually the AKS-74U became the carbine of universal choice.
The AKS-74U bridges the gap between a submachine gun and an assault rifle. The rifle's compact dimensions, compared to the AKS-74, were achieved by using a short 8.1 inch barrel. This forced designers to simultaneously reduce the gas piston operating rod to an appropriate length. Due to the shortening of the operating mechanism the cyclic rate of fire rose slightly to 700 rd/min. In order to effectively stabilize projectiles, the barrel's twist rate was increased from 200 mm (1:7.87 in) to 160 mm (1:6.3 in) to adapt the AKS-74U for muzzle velocities of 720 m/s (2,362 ft/s) and higher. A new gas block was installed at the muzzle end of the barrel with a muzzle booster, which features an internal expansion chamber inside the cylindrical section of the booster while the conical end acts as a nozzle to increase net pressure inside the gas chamber by supplying an increased amount of propellant gasses from the barrel. The chrome-lined muzzle booster also burns any remaining propellant, which would normally reduce muzzle blast. However, due to the extremely short barrel and conical end of the booster, the muzzle blast is nevertheless extremely large and visible. The muzzle device locks into the gas block with a spring-loaded detent pin and features two parallel notches cut into the edge of the flash hider cone, used for unscrewing it using the cleaning rod stored under the barrel. The forward sling loop was relocated to the left side of the carbine and the front sight was integrated into the gas block.
The AKS-74U also has a different sighting system with a U-shaped flip sight instead of the standard sliding notch rear sight. This sight has two settings: "P" (calibrated for firing at 350 m (383 yd)) and "5" (used for firing at distances between 400–500 m (437–547 yd)). The rear sight is housed in a semi-shrouded protective enclosure that is riveted to the receiver's spring-loaded top cover. This top cover hinges from the barrel trunnion, pivoting forward when opened, which also works to unlock the gas tube cover. Both the gas tube and handguard are also of a new type and are shorter than the analogous parts in the AKS-74.
The AKS-74U is significantly more maneuverable in tight quarters than the AKS-74; however, the significant decline in muzzle velocity to 735 m/s (2,411 ft/s) resulted in a 100 m (109 yd) reduction in effective range to 400 m (437 yd) (the effective hitting distance for a "running"-type silhouette target was reduced from 625 m (684 yd) to 360 m (394 yd). The AKS-74U cannot mount a bayonet or standard under-barrel grenade launcher. The majority of AKS-74U carbines were manufactured at the Tula Arms Factory rather than Izhmash. The AKS-74U also exists in a version featuring modernized synthetic furniture made from a black, glass-filled polyamide. The AKS-74U was also used as the basis for several other unique weapons, including the bullpup OTs-14 Groza specialist carbine which is now in limited service in the Russian military, and the Gepard series of multi-caliber submachine guns (none of which evolved past prototype stage).
No matter what people may say, this is still relatively a modern PDW, without the PDW. Effective range of the sights were still overestimating actual ballistic performance. Which meant do to sight options, the carbine itself is unable to make precise shot without a scope or sight replacement. Which is probably why there are more Eotechs or Kobras on 74 u's on special forces loadouts than any M generation 74.