This will stop a .22lr from anything 50 feet or more, without ricochet at any point on target stand. It can be built to any size you want. The center concrete section is 4 inch thick solid concrete block. The wings and secondary layer behind the blocks is 8x16 cinder block. The side shot shows the replaceable slats made from 2x8 pallet wood from some heavy pallets my work gives us for free. The particle board alone is enough for .22lr practice at 50 feet and more. it safely drops behind the pink foam after hitting the concrete without damaging the blocks. Many of my rounds don't make it past the second sheet of particle board since i use the 2x8 wood to staple all my targets to. My .223 is only shot at the thickest sections as shown in the side view with target stapled to the 3x4 upright. It and the ones behind it stop a .223 from 50 yards before it hits the pink foam. The rear shot shows how i stacked cinder blocks vertically to cover the vertical cracks between the solid blocks to avoid using mortar and make the whole thing easier to maintain. This also made it unnecessary for the ground to be perfectly level. I shot a .223 round at a seam and only dust made it through to the cinder block behind it....of course, the two 4 inch blocks had a 1/2 inch deep 2 inch diameter depression at those edges where they came together. Point is, nothing got through but concrete dust in a fine vertical line. the bullet jacket dropped to the ground behind the pink foam...fragments sprayed against the back of the foam. You can see a .223 bullet hole in the target where i tested it for penetration of those wooden layers from 50 yards. The bullet was effectively trapped in the wood before the pink insulation. This is a cheap investment for a safe location to make it even safer.