I come up with a great back stop/bullet trap for shooting Aquila .22 Super Colibri. I cut up a bunch of 2x4 blocks 3 1/2 " long, and placed them on end to form a tight fitting area around 21"X21" with a tight 2x4 frame around them. When you shoot, the blocks catch the 20gr bullets in the end grain, and when an area gets shot up too much, you dig the blocks out one by one and replace with new ones. This keeps the remaining blocks tight until you remove another one. I placed a sheet of rubber over the target area, to catch any bouncing lead, and a sheet of 3/4" plywood on the back. Simple to use and easy to hang on a wall. I use it every day and I think others will enjoy shooting just about anywhere.