Firstly, I'd guess that a large parentage of shootings are where the victim had no idea it was coming and a surprise, so therefore unable to defend themselves, so having a gun would have been worthless.
Wonder how many people have been shot by those *not* caring guns versus those who *have* been carrying guns.
Therefore if you ban guns and no one had guns, why would I need one to defend myself.
Moral of the story. Ban guns.