If more average Joes walking down the street might be packing, an "urban youth" might be a bit more circumspect about popping a cap in one of the rival community organizers.
More guns among the general law-abiding population means that fewer criminals want to publicly commit any faux pas that might cause a citizen to chastise him with an application of lead.
Remember the three requirements for a crime: Means, motive and opportunity.
A more heavily armed general population reduces opportunity, thus a lower crime rate.
Most murders are criminals killing each other and they know who they are .It isn’t some guy just walking down the street
A lot of the other murders are domestic violence
Legitimate gun ownership doesn’t affect these numbers so saying the drop of 10% is due to law abiding citizens owning more guns doesn’t compute