Threatening someone by using a gun (regardless of real gun or watergun or not) is ban deserving. As it's still a threat even if it's meant to be a joke. I don't suggest that kind of joke as it might hurt someone mentally.
BUT, getting banned from picking a fight with multiple users even though you have no obligation to do so is very silly.
Like, you can try not to care and settle things peacefully and be civil with the discussion (sportsmanship rules still applies on the internet, not just real life). And even if you don't disagree with their opinions or their philosophy, just say something like, "You know what? I don't agree with your opinions, but I can at least respect you for being entitled to your opinions. Let's just agree to disagree."
Then other users will sympathize with your opinion and go on. It's very simple and straightforward.
If you're a sensitive person or emotionally unstable, the internet is the last place for you to release all your anger/frustration/judgment.
If you're complaining about users harassing you or stuff like that, you have to look at yourself first and foremost, reflect on what you did for making other users trying to harass you, etc.
This is just my suggestion. Obviously there are better ways to settle things but this is my best approach.