The AK-47 is the most widely used, and a favorite, of fighting forces around the world. A big reason is because of how easily the firearm operates. The AK-47 is made up of fairly simple and large pieces, which allow for it to cycle in many different conditions, like sand, mud, and even water.
The moment the operator pulls the trigger, it releases the firing hammer then striking the pin. This will then ignite the bullet primer which ignites the gunpowder to launch the bullet. The pressure and gas that pushes the bullet out also pushes back on the bolt carrier, ejecting the empty shell, and resets the hammer to fire again.
The bolt will then grab a new round from the magazine, and place it into the barrel. During that action, the bolt hammer does not move because of the sear that is holding it in place, that is until the carrier returns to its original position.