 These ships would have rivaled the Imperial Japanese Yamato class and America 's planned Montana class in size if any had been completed , although with significantly weaker firepower : nine 406 @-@ millimeter ( 16 @.@ 0 in ) guns compared to the nine 460 @-@ millimeter ( 18 @.@ 1 in ) guns of the Japanese ships and a dozen 16 @-@ inch ( 406 @.@ 4 mm ) on the <unk> . However , they would have been superior to their German rivals , the Bismarck class , at least on paper . The failure of the Soviet armor plate industry to build cemented armor plates thicker than 230 millimeters ( 9 @.@ 1 in ) would have negated any advantages from the Sovetsky Soyuz class 's thicker armor in combat . 
