There's also Company B, 28th Massachusetts, an Irish Brigade unit, and the Brady Sharp Shooters, 16th Michigan. Both have people in suburban Virginia (a few of both in Arlington) and Maryland.
They and the 3rd US are all part of the USV and work and play well together at events throughout the year. They're also all friendly to beginners and have members who attend the full spectrum of events, from local living histories to mega-fests to progressive marches and tacticals.
An informal group, the "Loudoun Hampshire Mess" conducts monthly ten mile marches on the W&OD trail in Reston. Contact me for details at email@example.com
You're in a great area for reenacting. Good luck!
M. A. Schaffner
Midstream Regressive Complainer