Halo: Combat Evolved/Glitches

Backpack reload
An easy and yet invaluable technique for any Halo player, the backpack reload glitch allows a player to reload his weapon with the other weapon out. This glitch works as follows:
 * Have the weapon that needs reloading out. (This commonly happens when you were attacking with the weapon and the clip is spent.)
 * Hit the reload button twice, and then bring out your other weapon.
 * The reload animation will continue for the 3rd person view, and you will still hear the reload sound effects. However, you can fire and everything else as normal.
 * When the animation/sounds are finished, your weapon is done reloading, and will be reloaded when you bring out the original weapon.

Using this technique, you can cycle through two different weapons without ever having to pause to reload, which is what makes it such an essential skill.

Auto-reload
A harder technique to master, auto-reloading can be performed by pressing, then again, then  in quick succession. After this, the weapon will fire another shot quickly, and become reloaded.