The Koros M58, often called the M58 or Koros for short, is an assault rifle developed by Hatterleigh in 1958. It was loosely based off of a submachine gun design from the 40s that was never used, and it quickly became essential in the Hatterlese Military, as the need for an advanced assault rifle was a must have for every modern military during the time, and it was overdue for Hatterleigh. The gun is a gas-operated and uses a 5.56mm bullet. It is designed for mid-range engagements, and is customizable to an extent. In 1964 a citizen-use Koros M58 was introduced into the market and became a major hit in Hatterleigh, and made it's way into some other western nations. In the Olive War (1965-1969) the Koros M58 saw it's first major action and proved to be very effective, from which point on it became a sort of national symbol. It isn't used by Hatterleigh in military conflict anymore however it remains prominent with citizens, regional guards, and the Hatterlese National Guard.