Having some pitch variation for gunshots as well as proper sound looping should be enough. I don't see how adding multiple sounds for reloads would be useful. Things that do need additional sounds (more ricochet or death sounds for example) could be implemented as default instead.
But let's say there is some kind of sound modding - it should be a part of "Mod.ini" that we already have, under [SOUND] section. That was the goal behind mod.ini - to combine all special customizable properties into one file, instead of having multiple .ini files in different folders.