Also one thing to bring up too about the speeds is remember to factor in game lag too. If your Internet speed is not the greatest then it will also affect the rapid-fire. I have noticed that using rapid-fire on full-auto guns looks like your shooting bullets but when your shooting at someone it seems like the bullets do not actually hit the them....Werid.....
I get that all the time without a modded controller. It's just lag, nothing to worry about. I've shot someone 5 times with a shotgun, only to have them turn around and knife me. It's weird, but nothing to do with the controller.