You can use a gun to try and kill your opponent but it doesn't always work. You need bullets to use your gun, and each time you shoot, you use up a bullet (more about bullets and reloading is in the Reloading section.) a gun can only kill an opponent if you use it while they are reloading. If you are not so lucky, they might use rebound and send the bullet back to you. Or they might use sheild, where nothing happens, because the opponent is sheilding themselves. And finally, many people get it wrong on this one, if you shoot and your opponent shoots, nothing happens, You just keep going.