Before 2008, handguns were completely banned in DC. And they were only legalized because the Supreme Court forced them to. Even then, the DC government has always done its very best to make it as difficult and tedious as possible to legally own a firearm in DC, and that didn't change after the Heller decision. Heck, it's even illegal to own loose bullets or casings if you don't have the proper permits.
I grew up in DC. AlexanderA is right: If you like guns you're not going to live in DC. Even if you have to work there, you can still live across the river in VA where the 2nd Amendment has a lot more sway. And I can't even begin to imagine how a pro-gun voter in DC would be able to change anything anyway; it's hard to vote for pro-gun candidates when there aren't any.
Tomrkba: I'm no lawyer, but I'm fairly sure DC is allowed to ban carry simply because no higher court has ruled against it. It's the same as their previous handgun ban: You could claim it was unconstitutional all you wanted, but nothing was done about it until the Supreme Court addressed that subject in Heller.