This is my LEGO Technic Super shotgun from DOOM 2016. Although it is not entirely accurate, it is still pretty close to the real thing.

Supplies

I can’t be bothered to count all the pieces, so you will need LEGO technic pieces and at least 5 rubber bands.

Step 1: Shells

This step will tell you how to make the shells. Make at least 2 of them.
Pic 1: Parts for 1 Shell
Pic 2: Top of Shell
Pic 3: Sides of the Shell
Pic 4: Bottom pieces of the Shell
Pic 5: Trigger piece
Pic 6: Ram rod
Pics 7-12: Assembly
Pic 13-14: Banding
Pic 15: Finished Shell
Pic 16: Ammo

Step 2: Barrels

Pic 1: Parts for the barrels
Pic 2: Parts for barrel 1
Pic 3: Barrel 1 assembly (grey piece will be added later)
Pics 4-5: Important parts on the barrel
Pic 6: Parts for barrel 2
Pics 7-9: Barrel 2 assembly
Pics 10-13: Attaching the barrels together
Pic 14: Finished Barrels

Step 3: Handle

Pic 1: Parts for the handle
Pics 2-7: Assembly
Pic 8: Finished handle

Step 4: Main Body

The most important part of the gun
Pic 1: Parts for the main gun
Pic 2: Make this
Pic 3: Add this part here
Pic 4: make this
Pic 5: Add handle
Pic 6: Make sure to add blue pins here. (Your going to have to force it into place)
Pic 7: Add this
Pic 8: Add these (Black and white griders)
Pic 9: Add these
Pic 10: Add the side plates (both sides)
Pic 11: Add this
Pic 12: Add this
Pic 13: Add this
Pic 14: Add this
Pic 15: Put the band like this
Pic 16: Finished main gun

Step 5: Final Assembly

Final assembly is pretty easy. Line the holes up, push a rod through, add the caps, and put two pins here (closest holes to the trigger underneath the barrels).

Step 6: Firing

To fire, you first prime and load the shells. Then, you unlock the barrels and push the loaded shells all the way in. Next you close and lock the Barrels, and pull the triggers.
Pic 1: Primed Shell
Pic 2: Loading the shell
Pic 3: Unlocking the barrels
Pic 4: Loading the shells
Pic 5: Locking the Barrels
Now you are ready to fire