Actually, and someone here probably knows better. The grenade mechanism itself can be owned by people under class 3 paperwork. That is the mechanisms, without fuse and removed of the explosive medium. I know grenade launchers can be obtained through class 3 paperwork under the title destructive devise. The grenade with the explosive material requires more qualifications than I would even want to guess. I'm guessing a class 3 license and a top pyro license would not even qualify one to own grenades. Of course we can all get the recast paperweight look alike grenades, or old training and powder form grenades that have been made irreversably inert. I've got an old inert 'training' grenade on my desk with a "take a number" tag on it. Just an interesting though expiriment on how hard if impossible it would be legally. These grenades found at scene are of course most likely the bargain basement black market purchases that "according to all the quote knowing people, can be prevented by strengthening the laws". We see how well that is working. ARG!!!