Disabling Pirate/Outworlder raids?

[Boston]

So, I am playing as Tribals, and I want to limit access to firearms. Totally: I don't want them in my game. Unfortunately, if I get raided by Pirates or Outworlders, then when the attackers die they stand a chance of dropping firearms.

IS there a way I can eliminate those factions from the game, or just preventing them from raiding me?