The Daewoo Precision Industries K1/K1A is a South Korean submachine gun is the first modern firearm developed by Agency for Defense Development (ADD) and manufactured by Daewoo Precision Industries and entered service in the South Korean Armed Forces in 1981. Although K1 uses .223 Remington, it is classified as a submachine gun by the South Korean military and the current manufacturer S&T Motiv, because the K1 was intended to replace M3 submachine gun. Sometimes, either assault rifle or carbine are used to describe the K1 outside of South Korea.
In 1976, the Republic of Korea Army Special Warfare Command requested a new weapon to replace the old M3 submachine gun. In the following year, ADD launched a project derived from XB rifle, which started in 1972 to replace licensed M16A1s with indigenous weapons. Under the demands of the ROKASWC, the new submachine gun must acquire greater firepower, light weight, cost effectiveness, and easy access to spare parts. The first prototypes were made in 1980, and entered service in 1981 after series of field test. However due to the design of its flash suppressor, the K1 exhibited serious problems in service with the ROK armed forces. The original version had excessive recoil, noise, flash, and weak stock due to increase in firepower. These problems caused difficulty in aiming especially during night operation.
These shortcomings were later fixed by the development and adoption of a new flash suppressor, which has three holes in the top right quadrant to limit muzzle flip under rapid fire and reduces flash to one-third of that of the early K1. This new version of K1 is known as the K1A and its production began in 1982. All K1 submachine gun in service were subsequently modified to the K1A standard.
Most of the time, K1 submachine gun is regarded as a shortened or carbine version of Daewoo Precision Industries K2 assault rifle. However, although two guns share development history, two guns are very different from each other for the following reasons:
- The development of K1 was completed earlier than that of K2.
- The K1 uses a expanding gas piston-operated gas system, while the K2 uses a long-stroke gas piston system.
- The K1 has 1-in-12 rifling twist, while the K2 has 1-in-7.3 rifling twist.
The carbine version of K2 named K2C was developed and shown to the public in 2012 by S&T Motiv.
- XK1: Experimental prototype.
- K1: First mass-produced variant. Every K1 has been modified to K1A standard.
- K1A: Second mass-produced enhanced variant.
- MAX-1: Semi-automatic version of K1A for civilian market.