Some people have a hard time removing the barrel from their Tiberius Paintball marker. It's rather easy and I will show you how.
Remove the clip. This insures that with the air source removed, the weapon can not shoot. Paintball safety should be taken very seriously.
Push the barrel back towards the trigger and rotate counter clockwise.
This will release the barrel and the spring inside the marker will push it outward.
The barrel can be easily removed.
Reverse process to reinsert barrel.