Caveat Emptor:

While the method proposed here to measure rate of fire is highly accurate, it is nevertheless sensitive to various factors, most major of which is battery output voltage. A typical fully charged 8.4v battery exhibits an output voltage starting at approximately 10.4v and falls steadily as the battery discharges. As will be discussed in the upcoming AEG Motor Science article, DC electric motors display different operating characteristics depending on the input voltage. As a result, changes in the battery voltage inevitably affects the accuracy of rate of fire measurements. If separate rate of fire measurements are to be compared, it is imperative to either control or record the battery output voltage for each measurement, so that meaningful conclusions can be drawn.