The filenames don't exactly line up perfectly so you may still hear some arrow noises.
These are the how the sounds look in the MPQ.
Bow sounds:
Code:
Sound\Item\Weapons\Bow\ArrowHitA.ogg
Sound\Item\Weapons\Bow\ArrowHitB.ogg
Sound\Item\Weapons\Bow\ArrowHitC.ogg
Sound\Item\Weapons\Bow\BowArrowInFlightLoop.ogg
Sound\Item\Weapons\Bow\BowPreCastLoop.ogg
Sound\Item\Weapons\Bow\BowPullback.ogg
Sound\Item\Weapons\Bow\BowPullback1.ogg
Sound\Item\Weapons\Bow\BowPullback02.ogg
Sound\Item\Weapons\Bow\BowPullback2.ogg
Sound\Item\Weapons\Bow\BowPullback03.ogg
Sound\Item\Weapons\Bow\BowPullback3.ogg
Sound\Item\Weapons\Bow\BowRelease.ogg
Sound\Item\Weapons\Bow\BowRelease02.ogg
Sound\Item\Weapons\Bow\BowRelease03.ogg
Gun sounds:
Code:
Sound\Item\Weapons\GunFire01.ogg
Sound\Item\Weapons\Gun\GunFire01.ogg
Sound\Item\Weapons\Gun\GunFire02.ogg
Sound\Item\Weapons\Gun\GunFire03.ogg
Sound\Item\Weapons\Gun\GunLoad01.ogg
Sound\Item\Weapons\Gun\GunLoad02.ogg
Sound\Item\Weapons\Gun\GunLoad03.ogg
Here are the needed sounds in a .RAR file: http://uploading.com/files/m37ba7c4/...BWarcraft.rar/
Copy them into your game directory so that the folder structure matches.
I renamed the files as best as I could, made GunFire sounds into BowRelease sounds, and GunLoad sounds into BowPullBack sounds and put them into the correct folder.
You will be the only one that hears the change, all others around you will still hear bow noises.