Ruger

The Kruger (or Ruger) is the entry-level assault rifle in Grand Theft Auto: Vice City. It becomes available after the mission Guardian Angels. Being an assault rifle it is one of the weapons that can be manually aimed. Its performance is similar to that of the more expensive M4, the main difference being that it has a significantly slower rate of fire. It's named Ruger in the PlayStation 2 and Xbox versions, and Kruger in the PC version. The weapon is based on the real life Ruger AC556F law-enforcement version of the Mini-14 rifle.

Wikipedia has an article on:

Ruger

Locations

GTA Vice City

Vice Point - On top of the roof behind El Swanko Casa.
Ocean Beach - Available for purchase from Ammu-Nation after completion of Guardian Angels.