Be Seeing You,
Chris
But if you're considering becoming an unofficial "first responder" to an incident, that opens up a whole case of worm cans. Then you should consider a 12 guage if that suits you, or a Sport Utility Rifle in .556mm, 7.62 Russian, or 7.62 Nato.
Just remember that as you go dashing in to engage the jihadis before they can kill more innocents, the first arriving police are likely to shoot you if they see you holding a weapon, before they sort out who's who.