JBWeld would work. Quick-and-dirty you could use red locktite. Make sure that what ever you use it cant ooze into the bore. I would push the pieces together about 1/2" inch, then apply the magic goo. Carefully clean up any excess.
I splash anodized a bunch of Smartparts barrels back before the company wanted to, also to match exactly the splash anodizing I was doing to the rest of the gun. We used this technique to reassemble the barrels.