I used to work on miniguns in the military and I can tell u that the ammo is fed into the back section that little tube that sticks out of the side on your model it's called a feeder and ammo is fed in through that and into the bigger gun housing chambers the shot out the barrels. There is a chute that looks like a bunch of linked [_] Where the ammo is fed through. I know this may sound strange but if you need more then I can even give you some detailed pics too. I worked on many small arms including miniguns 50 cals m-9 ect....