Breech-loaders, muzzle-loaders, and the search for a reliable gun

The established 64-pounder was a capable and trusted muzzle-loader with a long service record and an effective range of roughly 4.6 kilometres. The ships were intended to receive Mark III guns, though performance records suggest that a few may have begun their first commission with Mark IIs. The first Mark I six-inch breech-loader promised much higher velocity and about 8,000 yards of range, but barrel deformation, an unfamiliar locking direction, and doubts about breech security sent the design back for improvement. The Mark II used a more secure interrupted-screw breech, fired a 100-pound shell, and reached roughly 10,000 yards, making it a much more convincing station weapon. The older seven-inch muzzle-loader hit harder but lacked enough range and improvement potential to justify its weight by the 1880s. The comparison shows why a weapon with better theoretical performance may remain a poor procurement choice until it matures.