Yeah... I eventually came across what seeems to be the definition that I was looking for.
I stumbled across it as I made a fix for another mod that didn't interact well with projectile travel distance and targeting range.
The solution was pretty straightforward for that mod, and I've posted on the modpage about the fix.
Now the strange thing was, I had that startup setting enabled (more-realistic-weapon) while trying to load this mod but it still failed to load at the time, but perhaps it would be prudent that I give this mod another go at loading, now that the rest of my modlist is working fine :)
This is something you could handle in your mod somehow, when the setting is disabled (and log a warning about it, at least).
if mods["Krastorio2"] and not krastorio.general.getSafeSettingValue("kr-more-realistic-weapon") then --[[ Handle the missing ammo, perhaps with a warning ]] end
Alternatively (the easy solution) you could skip loading in the definitions if the required mod option is disabled (although this could cause a data purge when loading a saved game - it would however allow the mod to load, but with a stern warning :)