I've used them a bit at matches. On sandy surfaces and grass they're ok. 10-20 cases pistol brass is the max. Forget thinking that you're going to sweep up all the brass in one pass. Go too fast and centrifugal force pushes cases out. Too slow and gravity drops them out when a new case is picked up. Rocks and debris cause them to fall out. But you can get a feel for the device and within its limits they are ok.