If you had a brain you would know criminals aren't going to make their own guns and gang bang. The penalty for having a homemade gun are much worse than having a real one and the cops will profile people to remove guns from their streets. The cops will use stats and focus on that area, searching people every day.
Most homicides aren't planned in advance.
It will become a booming industry. Where there is something restricted that people want, there is a black market for it.
What are they going to want, a five year felony conviction for being stupid? Once guys are restricted in cities, it's smarter to just avoid the hassle of having them and they can be removed faster than returned. A member of a gang is not going to want to be on the streets with a gun. They'll work out other ways to cope with the new reality.
A member of a gang is not going to want to be on the streets with a gun.
Care to explain why cities with the most restrictive gun control laws has the most shootings and gang related murders? Or are you going to keep saying stupid shit?