Dumbarton Castle was largely a tourist attraction by 1840 and was primarily garrisoned by volunteers. Young Queen Victoria visited the castle in 1847. During the 1850 and 1860s the adjacent river banks were used for shipbuilding including the building of iron hulled ships. By 1909 Dumbarton had been been transferred from the War Office to the Office of Works, although the military had largely moved out by 1865.
In 1842 Dumbarton Castle mounted some seventeen smoothbore guns, including three 18-pdrs and thirteen 12-pdrs. By 1866 there was a total of twelve smooth bore guns, increased to fourteen by 1867. Fort Dumbarton was disarmed in 1881. Dumbarton Castle was therefore primarily armed with smooth bore guns, many of which are still displayed with the castle.