Mk II followed the early weakly made and less powerful Mark I 80-pounder and introduced a 100-pound projectile, which became standard for British 6-inch guns until 1930.

It consisted of a much thicker steel barrel with wrought-iron jackets shrunk over it and as originally introduced weighed 81 cwt (9720 pounds).

The gun proved to be too weakly constructed, and 5 steel chase hoops were added to strengthen it and the gun was shorted by 12 inches to rebalance it, resulting in a bore length of 144 inches (24 calibres) and final weight of 89 cwt (9968 pounds), or 4½ tons.

Marks III, IV and VI became the most commonly deployed versions, and their widespread adoption would indicate they were considered successful.

Guns equipped the following British warships : Mk IV and VI guns were widely used in coast defence around the British Empire, both on hydro-pneumatic disappearing mountings and Vavasseur slides (inclined slides that absorbed recoil).

Britain was desperately short of heavy field artillery at the beginning of World War I, and in 1915 old BL 6-inch naval guns were shortened and bored-out to produce BL 8-inch howitzers as follows :[12] Mk V was a longer (30-calibres, 183.5 inch bore) unrelated Elswick Ordnance export gun.