A method and apparatus for loading cartridges into a gun magazine clip from a tray. Even if an inclined supporting mount or the like is not provided within a case, the memory board is set at an incline. Therefore, the lock of the compressor can be accurately detected. The ultrasonic transducer module is connected electrically to the output module for receiving the second drive signal therefrom, and for producing ultrasounds, the frequency of which corresponds to that of the second drive signal. Moreover, the method includes calibrating the first measurement system with the first plurality of calibration standards, obtaining a second plurality of calibration standards, and measuring the second plurality of calibration standards by the first measurement system to obtain a second plurality of measured values.