 The armament of the Minotaur @-@ class ships was intended to be 40 rifled 110 @-@ pounder breech @-@ loading guns on the main deck and 10 more on the upper deck on pivot mounts . The gun was a new design from Armstrong , but proved a failure a few years after its introduction . The gun was withdrawn before any were received by any of the Minotaur @-@ class ships . They were armed , instead , with a mix of seven @-@ inch ( 178 mm ) and nine @-@ inch ( 229 mm ) rifled muzzle @-@ loading guns . All 4 nine @-@ inch and 20 seven @-@ inch guns were mounted on the main deck while 4 seven @-@ inch guns were fitted on the upper deck as chase guns . The ship also received eight brass howitzers for use as saluting guns . The gun ports were 30 inches ( 0 @.@ 8 m ) wide which allowed each gun to fire 30 ° fore and aft of the beam . 
