Finally after many attempts and rebuilds, I made the lego APS underwater assault rifle.
It is featured in ghosts, but it isn't futuristic at all. It was actually made in the mid 70's. no instructions for this one - it was too hard to make.
Step 1: Stock
The stock on he gun is actually a wired stock. So it can slide back, buying wasn't able to make it fit with the pistol grip.
Step 2: Sights
These are the sights
Step 3: Magazine
The magazine is so big because it was made to hold small harpoons to pierce diver equipment like bullets in the air.
Step 4: Charging Handle
The charging handle also has to go a long way because of the size of the magazine.