Sniper Rifle M-16A12
Step 1: Cut the handle of the top of the M-16 so that both sides still have small stubs, but are still even.

Step 2: Take the smaller silencer from the Modern Special Operations Weapons Set. This will be the scope of the rifle.

Step 3: Glue the silencer on to the stubs so that the larger part of the cylinder is pointing toward the barrel of the M-16.

Step 4 (optional): Wanna make the rifle silenced? Then take the larger silencer from the same set as used for the scope. Slide the silencer on to the nozzle for a silent snipe.