No one is arming up in DC like you wish they are.
The post-Heller laws are still ridiculous and essentially an all-out ban. Gun laws are having a minimal, if none at all, impact on DC's crime rate.
For example, there's still only 1 FFL in all of D.C. He does not sell guns, only transfers at $125 a pop.
To register a single gun still takes multiple visits to a police station, and costs nearly eight hundred to a thousand dollars. The process includes mandatory training, having the police inspect and fire the gun, multiple appointments for fingerprints and interviews, etc. It makes California look fun.