For this post I combined a few phases together as they are all Detailing steps for the project. This is when I added in an ammo cage that helps feed the ammo into the gun along with mounting points on the other side so that this can be added into a Jet. 

I also added in a top for hose connections to fee the gun the power needed to run it properly. I also added in pieces for all the spinning parts inside the gun to mount onto and have a more visual look to how you view how the gun should work. 

As for the inner workings of a mini gun itself I couldn't tell you without further research, but I know there are lots of tinny and quite large spinning parts that is constantly feeding the gun ammo and spewing out the casings. If you look at the inner workings its a ton of cog wheels working together grabbing bullets spinning them to the proper locations and grabbing casings to fall out. If you actually want to do some research on the inner works its pretty interesting how they are designed.