Squelchy's Gun2Bow Sound Pack
Squelchy's Gun2Bow is not an addon but a sound pack.
Works with 5.4 MoP and is fully backwardly compatible
Its purpose is to replace the annoying loud gun sounds with the quieter bow sounds.
As of 4.0.1, custom .wav files are no longer supported by WoW so both .wav and .ogg files are included so as to backwardly compatable.
Please read the included read me for installation guidelines but basically :
To work simply copy the Sound folder (without alteration) into the Data folder inside the World of Warcraft folder.
The sound pack only works client side, so unless others in your group have installed the pack as well only you will hear the bow sounds and they will still hear the gun sounds.