 The shell of the nine @-@ inch gun weighed 254 pounds ( 115 @.@ 2 kg ) while the gun itself weighed 12 long tons ( 12 t ) . It had a muzzle velocity of 1 @,@ 420 ft / s ( 430 m / s ) and was credited with the ability to penetrate a 11 @.@ 3 inches ( 287 mm ) of wrought iron armour at the muzzle . The seven @-@ inch gun weighed 6 @.@ 5 long tons ( 6 @.@ 6 t ) and fired a 112 @-@ pound ( 50 @.@ 8 kg ) shell . It was credited with the ability to penetrate 7 @.@ 7 @-@ inch ( 196 mm ) armour . 
