They can be most likely employing "plated jackets" have a magnet to them see should they draw in a magnet. You then have steel plated copper coated bullets. Yet another simple exam. Have a pocket knife for the jacket Should they be plated it can Slash into it much easier https://madbookmarks.com/story19448097/the-smart-trick-of-buy-federal-243-ammo-100-grain-that-nobody-is-discussing