I added a front & rear tru-glow type sight to my turkey barrel. I basically sketched the outline on the barrel, and then roughened up the surface of the barrel with a dremel tool. Then I used a 2-part epoxy adhesive (don't remember the brand name, but the type you can buy in any hardware store), and epoxied it on. I allowed it to cure overnight, and then post-cured it in an oven at 100C (212F) for 1 hour, which optimizes the adhesives properties. It's been 2 years with no problems at all.