Full Credits to @Sheldon for his mod here https://www.gta5-hub.com/weapons/bfh-ro993-carbine-sound

I just renamed it to be compatible with the latest OpenIV

How to install:

Put the sound files from the weapons folder in /mods/x64/audio/sfx/RESIDENT.rpf/weapons.awc

make right click on weapons.awc and then export to openFormats (put it on desktop) then you will get a data called weapons.oac and a folder called weapons, put the files in the folder.
Then make right click while you are in the "RESIDENT.rpf" path in OpenIV and press import openFormats.
Then click on the weapon.oac file you have on the desktop

put mgn_sml_am83_vera.awc in /mods/x64/audio/sfx/WEAPONS_PLAYER.rpf