Brian,
I live in the area and can attest to there being no real shops any longer.. We lost the Trophy Room and Old Town Armory (in Old Town Alexandria) several years ago. If you have half a day to kill, you could go out to Middleburg, VA and visit David Condon's shop - he focuses on Civil War/Militaria but also consigns sporting arms which I've known a few folks that have found good doubles there over the years. There is a large gun show in Chantilly, VA on Nov 21-23 - not far from Ft. Belvoir and in the direction of Middleburg. This show still attracts a few dealers in sporting arms and a member or two of this forum usually has a table.. but mostly it's gone the way of the black gun with assorted tomahawks and space age jewelry cleaners..Ugh
-jmc
