Look on the bright side, most combat ships have at least one
gun.
RSN mostly has the 76mm. Other navies like
USN’s LCS has the 57mm
(eg mk-110). Some have 30mm (Mk-46). Some have phalanx. Some have
12.7mm MGs.
There are several limitations with current experimental gun
systems.
- Recoil too heavy for heavy-weight projectiles. Gun system
cannot tahan.
- Guns end up firing projectiles which cost as much or more than
missiles. End up missiles cheaper.
- Threat from small craft make large calibre guns useless.