Quite an interesting map, and a valid question. I think the answer lies in the fact that people don’t differentiate gun fear from knife fear from robbery fear etc. A general feeling of unease and fear of violent crime will lead to increased fear of gun crime. The media reports of gun crimes in the area may be low but the reporting of knife crime in south london has been feverish this last year.
I have to make the comment that shootings don’t represent all gun crime. I would be interested to see if the map looked any different if armed robberies involving guns were included.