Because your Releasing the trigger calling for the Audio to stop.
Don’t loop your audio for automatic shooting. Either use your timer or have the code that actually does firing call the sound.
example…
My inputs are in the character class. It calls an event in the weapon class.
Weapon class determines firing mode and calls a specific function/event to execute.
Said function itself handles everything for firing including the FX.
The code doesn’t rely on the input being pressed. If it fires a shot it finishes the chain of events.