M79 has a 2nd fire mod dedicated for shooting buckshot.
I was told by one of the devs that it's for the sake of realism, so that it sounds more like a real buckshot rather than regular 40mm grenade.
In my opinion functionalities realism > sound. This will make places that prevent meta-gaming to give out the M79, or at the very least the buckshot, especially PvP.
If you don't want to remove the function - I would suggest making a separate M79 that doesn't have this function, so people could use either the realistic-sounding one, or the realistic-acting one, depending on which one they prefer.