Yes, I'm sorry that's a small something I've missed. My def for the Railgun has a 1 at the end. RimWorld doesn't like that and complains, but still runs without problems.
I have a fixed version ready and will probably update this today or tomorrow.
Unfortunately then, if you already have a railgun, it may result in an savegame crash..
But as it's hard to get a railgun, I'm hopefull, that ist not too problematic.