Interarms did not have a retail outlet. You are thinking of Potomac Arms, which was Ye Olde Hunter in years past, both now gone.
Right on target.
Potomac Arms was located at 0 Prince Street, right on the Potomac River. The bottom floor routinely flooded at least twice a year.
International Armaments Corporation (InterArmCo, or just Interarms) was located at 10 Price Street. They also had about ten enormous warehouses in the surrounding blocks.
No connection between the two, other than being on the same street.
