Armstrong 7-inch Rifled Breech Loading Gun (1861 - 1902)

The Armstrong 7 inch (110 pounder) rifled breech loaded gun was constructed using Armstrong’s method of shrinking concentric wrought iron hoops over a toughened and rifled A tube. The rifling consisted of 76 grooves, and the shell was coated with a thin sleeve of lead that gripped the rifling. The 7 inch gun was ordered by the British Government, despite Armstrong’s view that the mechanism was unsuited to heavy guns. The first guns entered service in 1861, but it became clear in naval use that the shells did not have the velocity to penetrate the armour of warships of that era. While the Royal Navy then reverted to muzzle loaded guns, albeit rifled rather than smoothbore in 1864, the 7 inch rifled breech-loaded Armstrong guns were supplied to the coastal defence forts (Palmerston Forts) built during 1860 -1870s. Some of the 7 inch guns remained in service until 1902. Many of these Palmerston’s Forts were designed to protect major ports from an invading force that landed nearby and attacked