One of my saves has no ammunition for the cannons. It used to have them but after an update they vanished. Probably an incompatibility with another mod that I used back then.
I tested it and the ammo still exists. It just isn't an unlocked recipe. It can be unlocked in another save.

Now, I kinda don't want to uninstall the mod and reinstall it since that would basically let the biters lose on my base. Do you know any way to fix that?

In game, open chat and use following command:

/c game.player.force.technologies['research-name'].researched=false

Where 'research-name' is the UNLOCALISED name of the technology. I'm not nearby my PC at the moment, so I can't tell the exact name. You need to open mod's zip file, and inside look for technology.lua. In it find names for technologies that unlock ammo you're looking for, and use above command with each tech twice: once as above (with correct tech name obvioudly), and second time replacing "false" at the end with "true". This will reset that tech and give you correct recipes.

Be warned though, using /c commands disables achievements for that save (you will get a warning about it when running command for the first time).

Yeah.... that kiiinda is something I wanted to avoid.
Might have to use some mod to remove the biters for a while and do some maintenance on that save ^^'

Thanks for the quick reply though

Modded achievements are separate from vanilla (no mods active) and steam achievements though. So if you're looking for them, you won't get any. A bummer, since I only play modded these days, and that 20M green circuits one is a lost cause for me 😅

I was going for the 20M one, at least hoping to do so.
But yeah... just going to fail anyways. Had to use the console after all since I couldn't just reset some vanilla researches.

At least I got a chance to keep those biters away like that :p

For future reference, uninstalling the mod, loading the save, saving again, and then reinstalling the mod would also reset the technology - all mod turrets and items would be gone though.