This is very much a work in progress and new sounds will be added daily.
In the current version it replaces the following
Hunting Rifle
10mm (Both silenced and unsilenced)
Covert Pistol (Both silenced and unsilenced)
Double-Barrel Shotgun
.44 Magnum
First step
You have to go to \Documents\My Games\Fallout4 open Fallout4.ini
Find “sResourceDataDirsFinal=STRINGS\” and replace it with “sResourceDataDirsFinal=STRINGS\, sound\” without the quotation marks.
(Optional)
This can work with texture mods like The Eyes of Beauty if you make the line read like this:
‘sResourceDataDirsFinal=STRINGS\, TEXTURES\, SOUND\,’
Second step
Drop the folder containing the sounds in \Steam\steamapps\common\Fallout 4\Data
Start the game up and enjoy your new sounds!
