you have to take the shots per second with a grain of salt, as with the call of duty world at war speeds are a collection of different shot lengths that average out to ~11 SPS. The only real way to tell is to look at with an oscilloscope, and averageing the times of each shot. People can get ball park by counting instruction cycles, but it is still a ballpark, and a lot of people that make rapidfire from the opensource code dont even have an accurate way to measure this.
People claim to get 13 shots per second and that is fine but being a human being, you will never notice the difference between 11SPS and 13SPS, and personally I wont believe the 13SPS unless i read it on my scope, and see it not get capped. Not saying that it isnt possible, just saying that it really is minutia as an extra 2sps does not make it faster as there are still longer and shorter pulses, it all depends on where in the pulse loop you happen to pull the trigger.