you can buy this from the acid mods shop!!!
NEVER BUY ANYTHING FROM EVIL CONTROLLERS!!!!!
I just repaired two of thier controlers. they were the cod4 model and my friend paid $100 for a hack job. they used a 12f675 chip. and wired it to a constant power supply. what they do is write the code to have rapid fire on an extra button small like 2mm tact switch. then they pryed up the trigger and pushed the tact switch under the trigger. so when you pull the trigger slightly, it is normal, but when you pull it all the way the arm of the trigger pushes the tact switch and fires rapid. I have a few pics of this at home, I will post when I get off work. It was a shame he paid $100 for a controller that quit working after a month, no service or waranty, and then he paid me $20 to change it out and put hazers chip in for cod 5
it was only maybe 10 hours after the patch the guys on the fourms narrowed down the fire rate to make this work. acid mods posted the fire rate before evil controllers started selling there product, that they claim to be the only one that can do it. I have suspisions the the evil controler guy watches acidmods.