In case anyone is a NERF and Halo fanatic (I am), this will teach you how to make a NERF blaster combo that looks like a Halo 3 BR55HB SR Battle Rifle with no modification.
Step 1: Things You Need
You will need a NERF Rayven CS-18(N-Strike or Elite), a Recon or Retaliator barrel extension(Retaliator Extension looks better with Elite Rayven) , and any kind of scope(i.e. Tactical Scope) or any kind of light(i.e. Recon "Laser" sight/light), and paint(optional).
Step 2: Attachments
Attach the scope/light onto the top tactical rail of the Rayven, then attach the barrel extension to the front. You're done!
Step 3: Add-ons
Feel free to paint the whole thing black(leave the orange muzzle on the Rayven and barrel extension) to make it look more realistic. Maybe a light on the bottom?