Looking online through google, I punched up Depleted Uranium shells, there are some there that are quite close to the ones you show, albeit not exactly the same but more or less the same type of body shell but with warheads fitted, which makes the shells longer, they are even the same colouring. If you can get access to a Geiger counter, it might be worth you checking just for your own piece of mind, you dont want those around if they are in case you start to glow. I,m not saying they are but they are pretty unusual in design and ones I,ve never seen before, Steve T might be able to shed some light on them