A few ideas
Here are a couple of ideas:
Loudoun Guns in Leesburg
Virginia Arms in Manassas
If you want to shoot try Blueridge Arsenal or the NRA range in the HQ building
I think the shops have web sites.
Rather than gun shops you may want to try the Firearms Museum at the NRA Headquarters in Fairfax, plus you can shoot at the range below the building.
Glock 23-Don't leave home without it!