I like it! Did you undercut the wooden band? I can see the shadow...looks good!
Nope, what you're seeing is walnut, not a gap. I drilled out the square osage blank with a 1-1/8" forstner, then slipped it on a 1-1/8" tenon on the walnut blank that I drilled out with the 5/8" bit. Then I re-mount the barrel in the drill press with the band down, and drill out the band. I use a parting tool to create a lanyard groove, which results in a clean transition between the two woods.