Here is its page on Gundam Info, clearly state that the so-call "laser cannon" is merely a small caliber gatling gun. It also mention that it has single vulcan gun on head (the blacken area on its cheek, I think).
Japanese Wikipedia suggest that its size, the Earth Federation emblem on the shield, and lacking of beam shield, suggest that it's most likely used to be an experiment downscale MS in UC era (around the time of the Heavygun). --My girlfriend is a loli. 05:16, November 22, 2015 (UTC)
Gatling Gun change to laser Gatling Gun?