Rod, you're not making sense. What you just said is that the Flak 36 doesn't sound like itself?
Anyway, the sound is, I believe, like many other sounds in the game. It is intended to satisfy more than a single slot for sound. That helps to keep the download size for the game small, and also keeps the game speedy. I am not even close to having all of the sounds finished, and the sound pack size is already getting to be substantial. That is the inevitable consequence of having individual sounds for every gun, vehicle, and aircraft.
If you really don't like the sound just get yourself a copy of FMOD, record some gears going "clack-clack-clack" and make your own sound pack.