G&G outer barrel

[Lt3033]

I'm needing an outer barrel for my g&g cr16 raider gbbr, but I only need one that's about 4 inches long so that I can have a silencer that comes out of the RIS with the inner barrel going thought it, anyone have an idea if they are available? Or would it have to be custom made?

I'm wanting it to look like this;
image.jpg