Bat wrote:
You'll need a .gma file extractor, and then go in your addon folder, and extract M9K sniper rifle addon.
After that, just open the extracted file, and you'll find many many .mp3 sounds, just download some, and replace them ^^
I'll advise you GWtool, wich is a great .gma extractor.
Or just use the one built into gmod called gmad. Its in your GarrysMod/bin/ folder. Just drag the addon onto it and it'll create a folder containing the content in the directory of the addon