I'm quite sure that it is possible to use two different crack sounds for each bullet type in ArmA, one for "near" passbys, the other for distant bullets (50 meters away or more). It would probably be both more realistic and more immersive to change the distant crack into a "whiz". Also, these sounds depend on the bullet fired, so it's perfectly possible to add something better for larger ammunition (i.e. cannons, etc.).
I've changed and added many sounds to the game, but did not intend to "release them" at first. I should probably post a YouTube video to showcase the modifications and get some feedback, but I don't know how to capture ingame footage and save it to video... FRAPS?
Thanks,
Luca A.