The original Mk I short barrel of 18 calibres suffered from irregular velocity and hence accuracy, due to incomplete burning of the powder charge, hence only 20 were built.

[4] The gun consisted of a central toughened steel "A" tube surrounded by wrought-iron coils, with a trunnion ring and cascabel.

Rifling was the "Woolwich" pattern of three broad grooves, with a uniform twist of 1 turn in 35 calibres (i.e. in 166.25 inches).

[6] Ten 40-pounder RML guns were landed in Egypt in 1882 as part of a Royal Artillery Siege train formed for the Anglo-Egyptian War, however none of them were deployed in action.

[7] The guns were also deployed at Forts and Batteries around Great Britain to form part of the fixed defences.