In most jurisdictions, homicide is entirely justifiable when it is committed in the act of defending oneself or others from potentially lethal forces, where a reasonable person would conclude that committing murder was necessary to preserve those lives.

Sure but is it legal if you’re not in the act of defending yourself? If you just walk up to someone who made you mad, and shoot them? No. Which means there are legal limits on how you can use your guns.

Yes, murder would be illegal without just cause, but then it doesn't matter what weapon is used, does it? In which case, you're trying to blame the weapon, rather than the person. I agree there should be legal limits on what you can do to someone else's person, but that policy does not require placing unconstitutional limits on gun use.

It doesn’t matter whether what kind of weapon. And in fact if you go up to my first comment, you’ll see I used the more general term “arms”.

You’ve decided to focus on guns in your comments, but that’s not a distinction that matters to my point.