I am building a dueling tree for my grandsons. We want to shoot it with 9mm's. The guns will be a AR9 with 16 inch barrel and a Springfield XDM. I have been told that we should shoot pretty heavy boolits. The targets are 3/8 inch AR500. They also suggest that the tree be angled at 20 degrees forward to avoid boolit splatter, which will make it harder to move the targets. Any ideas. Thanks Don