I'm sure you've seen what a modded controller can do if you have played online on games such as Call Of Duty, Halo, Counter Strike or Battlefield.

Here's a really simple modification to enable you to shoot your Barret 50 cal like a P90.

UPDATE: There seems to a problem with certain controllers. There are Matrix controllers that use PWM for the LEDs and some which use a different method. To determine the type of yours, remove the battery pack of your controller. Above the right battery terminal, if there is a " TP-19" then it is matrix controller and it will work with this mod. If there isn't a "TP-19" than it is the newer CG version and it will not work.

Step 1: Ingredients

First off you will need,

A TT8 Torx Driver
Small Push Button Switch
Some Thin Wire, Any will do (I used IDE Cable)
An Xbox 360 Controller (Wired or Wireless, it works the same)
Soldering Iron
A Drill and Drill bit (To match the diameter of the thread on your switch)
Some form of surface to work on. (I used a window ledge, I suggest you don't)

Step 2: Dismantle

Taking the battery out reveals another screw, its underneath the barcode sticker.

There's 7 screws Torx screws to remove

With the buttons facing DOWN, separate the two halves carefully, paying attention to the motors.

Step 3: Drill

Find the best place to put your switch. Choose very carefully cos once you've drilled you cant remove the hole from your £30 controller!

Once you have found a place, put the two halves back together and double check there is enough room for your switch to go in.

If there is, remove the circuit board so that it doesn't get damaged and drill away.

Step 4: Switchin

Put the switch in your new hole. Make sure that you orient the pins so that they are not getting bent or squashed when the controller is back together. I had to remove some of the motor holder to fit my switch in.

Step 5: Soldering Time

Heat up the soldering iron, not too hot or else it might break some components.

Point one and two are in pictures 2 and 3 respectively.
An final overview is in picture 4.
5 and 6 show the switch.
7 shows what happens when your iron is too hot and you take too long to make a joint.

Make sure wiring runs stay clear of the black button pads, analogue stick movement and screw holes.

Step 6: Put It All Back

Are the switch pins going to make contact with anything on the other half of the controller when reassembled?

Are all of the wires free from places of movement or screw holes?

Are the solder joints correct and not dry?

Are all of the annoying black pieces of the controller back on their positioning pins?

Has your soldering iron made suitably sized black marks on your window ledge?

Four out of five is good enough to continue.

For a quick test, replace the battery and depress your switch all the way. If the player one led lights up very dimly, then the mod worked!

Now try putting it back together without breaking anything.

Step 7: Done!

If you are having trouble putting it all back together, try wigging it while applying gentle force, and make sure all wires and button rubbers are not obstructing anything.

Here it is in action!

Step 8: How It Works

This works because to light the LEDs (on some boards with the crystal described in the intro), the Xbox uses Pulse Width Modulation (PWM), which sends the power to the LEDs in quick pulses. This mod uses them pulses to trick the Xbox into thinking you are pressing the trigger really quickly.