I've created a selection of impact particle effects for when bullets hit surfaces. I have them stored in a particle library called ballistic_impacts. I then have an FX library file called ballistic_impacts in my Game\Libs\MaterialEffects\FXLibs\ folder. How do I tell bullet/weapon to use these impact effects when hitting things?

Never mind, I'm pretty sure it's defined in the MaterialEffects spreadsheet. (I was convinced it couldn't possibly be in the spreadsheet for ages so I didn't look).