Although militaries are fond of making grandiose announcements about prospective weapons systems that don’t end up amounting to much, this is the real deal.
The idea of the railgun is nothing new. The French thought up the concept almost a century ago, the Germans came up with the first viable designs during WW2, and there was interminable work on them by both the US and the USSR during the Cold War – the concept kept stumbling upon the twin challenges of barrel wear and power generation.
But technological progress is now finally making them practically realizable and once they deploy on a large scale they will revolutionize naval warfare.
You can have thousands of projectiles on a destroyer versus the 96 missiles a typical US destroyer is currently limited to. They do not pose an internal explosion risk. Like cruise missiles, they can be precision guided. Unlike cruise missiles, they approach from a ballistic trajectory that is more difficult to counter, they are far smaller, and they are capable of much more rapid fire. It should in fact be trivial to deliver a simultaneous barriage of several projectiles from a single railgun by angling the barrel over time in an appropriate pattern.
Moreover, the technology syncs very well with concurrent developments in free-electron lasers (FELs). Indeed, the same power plants that enable railguns can also power FELs. If one can already imagine the day when railguns will become a viable defense against cruise missiles, with the possible exception of the latest hypersonic ones being developed by Russia, then prospective FEL systems will all but annul them by providing an extremely potent point defense around the warship.
There has been some talk in the past two decades that the proliferation of cheap cruise missiles, which can be easily concealed within freight containers, might herald an end to modern “gunboat diplomacy” by providing Third World countries with an affordable deterrant against even the most technologically advanced navies. One consequence of these developments is that these visions are highly unlikely to ever get realized, with the advantage remaining firmly on the side with the advanced navy.
The US currently has the lead on railgun development, but China at least is not far behind. Their next destroyer model is basically going to see a convergence with that of the Zumwalt:
The China Aerospace Science and Industry Corporation (CASIC) has reported online that its 206 Institute, which researches electromagnetic launch technologies, has made breakthroughs in electromagnetically launch boosted missiles and railguns designed for close in weapons systems (CIWS)… There have been online rumors that suggest that the second batch of Type 055 guided missile destroyers (potentially to be termed the Type 055A, following the naming pattern) will be armed with large railguns in the place of older 130mm cannons, for long range anti-surface and air defense warfare. The putative Type 055A destroyer class would likely be launched after 2020, and feature integrated electrical propulsion, for increased power generation to power railguns, lasers and advanced sensors.
Russia also claims to be developing railgun technology, although the lack of any concrete evidence suggests that it is lagging considerably (it’s not like Russia tends to refrain from showing off its weapons platforms on principle). However, this is probably not a major issue, since the railgun will enjoy its greatest utility at sea and Russia is primarily a land power.
In the prospective Great Power naval wars of the future – say, 2050, between China and the US – an extrapolation of current trends would suggest a conflict dominated by almost or completely automated destroyers or cheap “arsenal ships” firing autonomously-guided railgun volleys wherever their drone “eyes and ears” detect an enemy presence or even just based on probabilistic models (military satellites having been knocked out in the first days of the conflict and any further complex space activity having been made unfeasible for the next few decades).
Of course in this new environment surface ships will be in more danger than ever before, so the next logical step would be to install railguns on submarines. Or revive the old Soviet “dive boat” concept of a surface warship capable of shallow submersion.