The House has voted to uphold a provision of the Constitution...

now it's time to call your Senators and tell them to do to same.

US Constitution, Article I, Section 8:
Clause 17: [The Congress shall have Power ] To exercise exclusive Legislation in all Cases whatsoever, over such District (not exceeding ten Miles square) as may, byCession of particular States, and the Acceptance of Congress, become the Seat of the Government of the United States.

From The Washington Post:
The U.S. House of Representatives voted overwhelmingly yesterday to repeal one of the District's gun restrictions, prohibiting the city from spending funds to enforce a law that requires any firearms kept at home to be unloaded and disassembled or bound by a trigger lock.

It's about time that Congress does something that removes restrictions on the rights of US Citizens to defend their lives and homes.