I doubt that the gun restrictions being loosened has much to do with it. In the parts of town where there are killings, there are plenty of guns. And I don’t recall of an arrest where an “illegal” gun was used in self defense. It’s usually an add-on charge to something like drugs in a car (”illegal possession”).
What isn’t mentioned here is a several effort at upgrading the quality of the police force and its command structure. That has been truly impressive.
I flat out don't believe that. DC probably has a lot of good beat cops and inspectors, but command is pure politicians that get to play with guns, or the district wouldn't be in the trouble it is.