When Sora101Ven release their finished version of Ash's original mod of the "MW2 Reverb Replacement". One category of firearms had me disappointed when I fired a weapon, the shotguns. They still sounded vanilla! So I went ahead and fixed this, and used the punchy and bassy sound that MW2 has.
Sounds: Infinity Ward | Activision
This may not work 100% of the time if used with Sora101Ven's mod due to overlapping files, but I'm not 100% sure!