A 3D animation showing how an AR-15 works. Cinema 4D was used to create each individual part, as well as animating everything. Corona renderer was used for final output of lighting and textures.
In the word of my old drill sergeant, bullet goes into the mag, and you jam that mag into the mag well, press the trigger and bullet comes out on the other side. Just don't put the mag backward or in reverse and you will be fine.