Armstrong's 40-pounder rifled breech-loader worked well, but scaling the mechanism to 110 pounds proved troublesome. Accounts of the 1863 bombardment of Kagoshima give different explanations of its failures. One describes a breech piece blowing out and the concussion knocking down its crew, followed by an order to fetch a spare vent piece. An account published in The Times on 25 April 1864 reports no injuries from a broken vent piece and blames failure to insert a tin cap. That account praises the gun at long range and on a pivot mounting when properly handled. It criticizes broadside use between decks because of smoke, slow handling of the heavy carriages, and damage to the deck.
Chapter · 54:30-57:06
Armstrong guns and breech-loading risk
The successful 40-pounder and troublesome 110-pounder exposed the limits of scaling Armstrong's breech mechanism, with Kagoshima accounts describing failures and handling problems.