The stats are identical to the original minigun so it's not overpowered, it's just cosmetically different. You will find the minigun in a room under the overpass which is right by Novac. There will be one creature guarding it. The room that holds the gun is also a very small player home, with a bed, a cooking fire, and a few basic containers to store your stuff.

http://www.newvegasnexus.com/downloads/file.php?id=42593

Screenshots are visible at the Nexus.