I don't know about the laws regarding guns where you live, but in your article you are thinking only about the harm of a gun/bullet.
A gun is a tool. It doesn't always kill someone. Sometimes it can simply stop them immediately.
When I think of your story, and taking a bullet for someone I understand it, and I completely agree with you about the sacrifice.
The people with guns could be the government/authorities or criminals as you said.
Not only would I take a bullet for the people I love, but I would fire a bullet to protect them. And that's why I choose to own one, and practice being accurate with it.
I think it's important that if there are people who could harm us with guns, we the people, should be able to stop them with guns.
Not intending to kill, but to defend.
I know this isn't possible everywhere as guns are not legal to civilians everywhere, but I think we should be able to defend ourselves without relying on the police or governments.
I believe killing is a crime, and a sin. But to defend, is not only justified, but righteous.