Franchi,
I stop The Gun Shop from time to time and agree with Ken and KYJ - fair prices and good folks to deal with and talk guns with. Always some interesting doubles in the cabinet - American and Brit guns mostly but occasional German or Belgian oddity. A friend of mine has bought an extremely nice Army & Navy 12 bore sidelock that is 1 of a pair... currently trying to track down its mate.
Any how, its about Northern VA's only shop where you can find nice old doubles and a proprietor that knows them.
Best,
jmc
