BXR

BXR is a somewhat-complicated move that can be used with any weapon within Halo 2. The procedure involved has the player pressing the buttons, "B, X, R" in rapid succession, causing a melee attack instantly followed by round(s) from whatever weapon the user is holding.

This move is most often used in Team Hardcore by those experienced with the Battle Rifle, where it becomes an immensely effective combat type, for the strike will first take down shields, and if aimed right can provide an instant kill.

MeleeFire: B,X,R or B,Y,Y,R As soon as your melee has hit your opponent and the damage is done, you can cancel the rest of the animation with X and open fire again. If done optimal it will seem like a melee and shot at the same time. To be done with a full clip or using Y,Y instead of X when not. Strangely enough, you will automatically get a full clip some time after a BXR, even if you shoot. Also works with sniper, but preferably press X before the melee hits so you are still moving towards your opponent and can get a clean snipe. Note - When you don't have ammo to reload your battle rifle, you can keep doing B,X,R

On a second note when using the Battle Rifle you must have a full clip. Attempting a B,X,R with any ammunition missing will cause a shot and reload, failing in the attempt of the attack. however, if all of you ammo is expended except for the currently loaded clip (you have no more ammo to reload, only what is in the gun) you can BXR constantly (until the clip is expended)

Halo 3
The Mauler can be used in place of the BXR, just hit R, then B to instantly kill opponants.