I don't have CM:BS since I, A: Don't have the money and B: Am not really interested in modern day settings.
However, should anyone feel like making a soundmod, feel free to use my soundmods as material if you like any of the sounds.
Personally, I'd say that modern weapons have a slightly different sound than most of the WW2 weapons, but that's up to each to decide.
Anyway, feel free to use any of it and publish it.
Just remember to cite where you got the sounds in a ReadMe file (not because I want the credit, but because the sounds in my sound mod are not created by me and crediting my soundmod will in a way credit those who I credit in my soundmod... if that makes any sense)