I have no clue about that particular sound is, devs might know. The one you found might be particular to proj rifle, as it makes a different hit noise (AFAIK)
The only thing you can really do is run on OpenJK, you can do it through the launcher. I'm still adamant on figuring out what fixes it though. What graphics drivers do you have?
You could try what @ent suggested, I had no luck with it.