BA Minigun - proto to prod comparison
The barrel of the production minigun is about 1/16" longer than the prototype. Aside from the obvious fact that it's now molded in multiple parts, you can also see a number of other changes: the ridged stops at either end of the foregrip are gone, which is helpful for getting creative with posing the minigun. The grippable protrusion on the side where an ammo chain could be attached has been replaced with a much nicer-looking bar with a notched recess to allow room for the clip to rotate, so that the chain doesn't have to stick straight out.
Image for a review of the production Minigun on the BAF.