If the outer barrel comes loose on your G&G CM16 Raider-L or Raider-S you can re-attach it by following these instructions.
Tools needed: 2mm hex key
Step 1: Re-insert the outer barrel over the inner barrel of the gun. Make sure that it is facing in the right direction, then genly push it into position.
Step 2: Makre sure that the barrel is lined up correctly.
Steo 3: Using a 2mm hex key, tighten the barrel retaining screws on each side of the gun. You can access them through the RIS (shown below).