Halvor, check out my sticky on sounds
The sound itself is good, but the quality is slightly dodgey. The main problem with it is the reverb. It's indoor reverb that wouldn't work in game. One of the trickiest things in my opinion is creating good, realistic sounding outdoor reverb.
Too put your sound in game you just drag it over the old ak47 sound found in the objects_client zip file. Make sure you name it the same as the old one so you're replacing it, not adding it......just check out the sticky
