This is a mod which fixes an issue of one shot sounds like two in auto-fire mode for IZHMA and Grimm (akimbo and basic) shotguns.
Fantastic Auto Fire Sound Fix (Updated) mod for some reason doesn't fix specifically these weapons.
My mod is fully based on Auto Fire & Reload mod made by Hoppip.
Place in your mods folder.

USE SINGLE FIRE ATTACHMENT FOR THIS MOD TO WORK

WEAPON WILL FIRE IN AUTO FIRE MOD WITH FIXED SOUNDS

You can also add any other weapon ID to whitelist in mod.lua