brings up an old argument: how much ammo should you carry?
Ok, this is messy and nasty for two reasons:
1: The possibility of being attacked by a damned mob howling for your blood, and
2: No matter the circumstances, the left(which includes much of the media) will portray anyone who uses a gun to defend themselves/their family or friends from said mob as a nasty right-wing bastard who MUST HAVE WANTED TO KILL PEOPLE, because otherwise why have a gun? The fact that said howling mob was planning to beat you into mulch will be incidental; you using a gun to save yourself will be the 'crime'.
Complicating this is a bunch of professional agitators who will try to push things right up to the edge but not quite over to try to make someone fire a shot so they can scream "Evil gun-toting right-winger nazi* attacked us!" and claim victimhood. You hit one of them, even kill one, that just makes it better; they can shed even more tears and scream for the cameras. And they don't really give a rat's ass if one of theirs dies(we're talking, especially, the professionals) because The Party/Movement Trumps All. So if you hold off, no matter how hard they push, you don't give them that; but mobs are nasty things, and if they get too close, too worked up, one of them is likely to decide "It's time!", and everything goes to hell.
And we're back to the original question of "How much?" If you've got the answer, I'd love to hear it. One shot in the face of said mob might break them, as a lot of these clowns are used to thinking "Bash the Fash!" and actually getting shot at, let alone hit, is not in their vocabulary. The really dedicated, sure; but most of them aren't, I don't think. Other hand, this not being tv, anything other than a head shot might not make someone just fall down, and to a howling-for-blood mob a sound that in other circumstances would back them up might be barely noticed.
Best of all is to stay the hell away from such, if you can("You can't lose the fight you don't get into"). If you're caught in a situation without a way to get out, then 'as much as you can reasonably carry' is the amount: at least one spare magazine. Two or more might be great, but not everyone can carry that on their person.
Y'know, this is a really nasty discussion. And every time some idiot politician calls for 'confrontation' of anyone they don't like, it gets more likely some poor bastard is going to be caught having to deal with it.
*Yes, I know; yes they're that stupid.