Many, many moons ago I found a rifle cartridge and being the curious kid (about 12) I pulled a bullet to see what was inside. Then I wondered how that thing in the base of the case did what it was supposed to do. I picked up a nail and set it on the primer and lightly tapped it with a hammer. Yep primer went off, quite loud but the surprise was the primer was strong enough to travel up the nail and hit my finger, the side of my left ring finger. Well it hit hard enough to split, not cut, the skin and hurt like he**! IIRC the wound took a while longer to heal, maybe from an impact injury and all the bruising. 65 years later and I still have not repeated the experiment...