I don't know if anyone is aware, but radiation damage seems to bugged when used as a weapon against NPCs. I've tested it numerous times, and my weapons with radiation damage from the Legendary Modifier seem to cause no bonus damage whatsoever against NPCs. Human, Super Mutant, Ghoul, or otherwise. Also, the Gamma Gun, the only naturally radiation type damage in the game causes wonky and unpredictable damage to opponents, no matter if they have zero radiation resistance. You can shoot a human settler with it and it will do about 20 damage to them. It has a rating of 110... Can someone explain this please? My character spent 4 points maxing out Nuclear Physicist only to have it gimped by a damage type that doesn't even function?
I've tested this extensively using console commands. It definitely doesn't function.