I'd be more than happy to share what I've learned with a fellow shooter. I'll see if I can send a PM to you with my email addy. I also see where we're not all that far apart. I live in Cozad, NE.I'm in the process of designing my 100yd tunnel. Landy, I wonder if I couldn't have you bend my ear one of these days. Would be great to learn what you'd do again and do differently if you were to do another one.
Here's a pic of my tunnel shortly after it was constructed.
Landy