A free mod for Fallout 4, by pauderek.
If you're looking for a way to get more firepower in your guns, the Shell Rain mod is just the thing for you. It does exactly what the name implies: it adds more shells to your weapon, making it more powerful. The effect is most noticeable for shotguns and rifles. There are two ways to activate this mod: you can either set the value of fGunShellLifetime to a higher number, which will make the effect more powerful, or you can set it to a lower number, which will make the effect less powerful. The number of shells is increased by a factor of ten. This change is permanent, and it will stay this way even if you uninstall the mod.