Again for those with money to burn, you can this Clasic Army Minigun which is available for US$2,973.90 at Hobby e-Shop for those willing to buy it. This only fires on full auto, fully CNC'd with 6 barrels which rotate gatling-style. The barrel rotates using a 12v barrel while the projectiles are expelled using top Gas/CO2.

Classic Army M134-A2 Vulcan Minigun