I mentioned London because Dan Dicks mentioned it as an argument for a place with gun control and high crime.
Putting a narrow view mindset over me doesn't really help your case. I rather see your view narrow because there is only bad use for a gun and that is intimidation, pain and death. There is now way around a negative spiral and as soon as you allow that kind of weapon or actually any kind of weapon, specifically designed as such, into your life you have a problem more than less.
In the Hermetic teachings it says "As above, so below. As within, so without." Be careful what thoughts you project onto your reality. Gandhi didn't win India's freedom with guns either.
You try to fight fire with fire.