For those who do not know how to do this here you go.
This tutorial shows you how to cahange for example the sounds of the g36e to the sounds of the famas G2.
You will need Rezextract and Rezinect, download at the bottom
Open Rezextract click file, open to extract
Since Famas G2 is an assult rifle you click on GUNS_SND_AR.rez and click open
This will appear, wait until it says extraction complete then close Rezextract
Then go into My Computer go to your game folder and drage the folder made by Rezextract to your desktop.

You can go into the folder and there will be gun names in more folders, if you click on them, your default audio player will pop up and you can listen to the fire, the multiple reloads and several other sounds for that gun.

Now when you decided which sound you want for the g36e, in this case the Famas G2 sound, open up Rezinject click the button highlited in the picture, the navigate to your game folder and select the rez file where the weapon you want to put in the famas g2 sound is, this case g36e so GUNS_SND_AR.rez

Then click add, go to the folder in the desktop, go to all the famas g2 sound files, highlight them all and press open.

You will notice that all of the files say duplicate, what you have to do is press where it says click here to resolve and since its goint to the g36e scroll down till you find g36e. Do this for every file. Then press inject, once it says inection complete close Rezinject.
Almost done. Now go into my computer, go to your game folder, find GUNS_SND_AR.rez or whatever you inected into, then back it up, now find GUNS_SND_AR.rezNew and take the new out of it. Now play combat arms with your sweet sounding G36e, this can be done on any gun.
If you need help PM me. Ill be happy to help you
Virustotal:
Virustotal. MD5: 88319d153bafd4510d5aedb2c250cd9c