I have a couple of HDDs that I've pulled from computers that came from school. Most of them are dead(i.e. won't spin up or click when powered on), but I'm still obligated(as a condition of my taking them) to render them in such a state that the data can't be recovered from them. I hate to do this to Apple OEM hard drives, but at the same time they're not doing me any good and I also need to do my proper duty to ensure that the supply of computers does not dry up just yet. I'm thinking of using them for target practice(I expect that a well placed 357 magnum should do the job), but beyond that I'm wondering if anyone has any sure-fire, secure ways to destroy a dead hard drive?