Someone made something like this before, but their's didn't shell eject. All you have to do is stick in a shell, cock the gun, and fire. When you fire the shell ejects automatically. This gun uses a TR style stock and trigger, so you can use any kind of TR stock you want. K.B.S. stands for KnexBuild Shotgun. Please rate, comment, and SUBSCRIBE.
Step 1: The shell ejecting mechanism.
Image 1: Build this.
Image 2: Here is a closer view of one part.
Image 3: Here is a view at another angle.
Image 4: Here is a view at... ...Oh for Pete's sake, just look at the stinking picture!!!
Image 5: Add two more layers onto the stuff you made.
You're done with this step.