You ask a direct question and deserve a direct answer.
NO! Possession of an unregistered firearm in DC is a felony, and there is no way a non-resident can register a firearm in DC. Possession of ammunition without a correspomding registered firearm is a felony for each round of ammunition.
Given the number of metal detectors and other searches one is required to submit to in DC - think entering any government building amd many other public buildings, plus many private buildings as well - the odds of getting caight are quite high. Unless you would like to extend your vacation by several decades, I'd follow the suggestion to stop in Virginia and leave the hardware in the hotel/motel while visiting the seat of government.
Also remember that Maryland does not like to honor FOPA unless you are passing through non-stop (meaning they have not stopped you for any reason). New York and New Jersey also pose problems for you. I'm just going to presume you will take the long way and avoid Massachusetts and Connecticut altogether, so will not get into their peculiarities.
stay safe.