There is one sound file for all coaxial mgs, there is a reason why i titled that one GENERIC
Let's quote myself: "Generic Coax MG External (be aware that most tanks share the same sound in that case, that is why, I kept it as generic as possible)"
Internally you will have the M240 sound, but i cant do much about the external sound without making it sound wrong on other types. So i did the same thing as the developer. GENERIC
If I am not mistaken the turbo sound is part of the stock SBsounds, pls try if that is the case.