I'm also looking for something similar for a mod of mine. The problem is gathering all those sounds is quite a chore. Your best bet is to find a moddable game and extract some sounds from there.
I don't know if that would be legal though.
Another option is to scour sound libraries. It should be easier to get all those sounds from different sources (just look for the real gun sound, not the specific sample used in BF3).
Here you can search by gun model:
http://www.partnersinrhyme.com/soundfx/warsounds.shtml