I had an issue like this not so long ago.
It was a custom weapon i had made and the sounds weren't synced properly to the correct animations. So, when the character pressed 'W' to move forwards, it played the 'fire' sound.
Have a look at the sound loops and check what animations they are set to.
when you open the gunspec it will list the sounds followed by two numbers (ie, 64,2) the first number is the animation frame where you need the sound to start and the second number is the sound file you need to play.
Hope this helped.
Unfamillia
