What are grenades made from?

If you look at a hand grenade, it looks a bit like an egg. It's got a hard metal shell around the outside and it'' packed with high level explosives. At the top there's a trigger, and on the trigger is a really big spring. The spring pushes down on a hammer which pushes down inside the hand grenade. When you hold the handle closed and the pin is in it, it's compressed and can't go anywhere. As soon as you pull the pin out and let the handle up, it drives the hammer down inside the core of the hand grenade. In the bottom of the core is a detonator and it fires that off and lights a fuse. The fuse burns slowly for however long the grenade has been designed to burn for and that fuse detonates the main detonator and charge. This occurs a certain time later. The idea is that you know roughly how long it takes to go of, because when you lob it, it doesn't give the enemy an opportunity to pick it up and throw it back to you.