English 18th century light dragoon flintlock holster pistol, made in London. The stamped letters below the crown actually read GR. These initials are the reign mark of George Rex, meaning King George. I'm not certain whether this GR stands for George I, II, or III; the three successive reigns span 1715 to 1820. British royal arms have been stamped with reign marks since 1627, under Charles I. The Tower of London was first used as an armory in 1339. TOWER has been stamped on all arms ordered or stored there since 1699. The Master of Ordnance at the Tower contracted with private firearms makers to supply the royal arms. When the contracted weapons were delivered to the Tower and approved, they were stamped TOWER. The symbol is the Broad Arrow, in use since the reign of George I (1714-1727).