Guns are no longer used in ship to ship combat, but in clearing away small surface combatants, firing warning shots and shore bombardment. The 57mm Mk 110 is actually a Bofors design and, as the Wikipedia article points out:
“While the 57 mm cannon may not seem as powerful as larger naval guns, such as the OTO Melara 76 mm, some of its performances are comparable; given its rate of fire and amount of explosive per shell, the Bofors gun actually achieves a higher amount of “explosive fired per second” than the 76 mm.”
https://en.wikipedia.org/wiki/Bofors_57_mm_gun
Rate of fire is very much higher than the 76mm and it carries a LOT more ammo on the mount. Other thing is that the 57mm is agile and fast firing enough to be used in a defensive anti-air and anti-missile role, where the 76 really isn’t.
220 rounds per minute, with a capacity of 1,000 rounds, in a gyro-stabilized gun, would make it very effective against swarms of small boats.