In the US, there is speculation that the Zumwalt-class destroyers could eventually feature railguns, a possible alternative to the Advanced Gun System guns that the Navy might end up scrapping.
Skeptical about Chinese capability re. its new weapons systems, seems like the "superweapons" hype is promoted before public demonstrations. One the other hand, as a security-conscious taxpayer, the US debacle re. the Zumwalt destroyers pisses me off.
The National Defense Authorization Act For the Fiscal Year 2007 (Report of the Committee On Armed Services House of Representatives On H.R. 5122 Together With Additional And Dissenting Views) stated the following:
"The committee understands there is no prospect of being able to design and build the two lead ships for the $6.6 billion budgeted. The committee is concerned that the navy is attempting to insert too much capability into a single platform. As a result, the DD(X) is now expected to displace more than 14,000 tons and by the navy's estimate, cost almost $3.3 billion each. Originally, the navy proposed building 32 next-generation destroyers, reduced that to 24, then to 7, and finally to 3, in order to make the program affordable. In such small numbers, the committee struggles to see how the original requirements for the next generation destroyer, for example providing naval surface fire support, can be met."
Prompted by the 22 November 2016 break-down of Zumwalt in the Panama Canal, with both propellers seized, Mike Fredenburg analyzed the program for the National Review and concluded that the ship's problems "are emblematic of a defense procurement system that is rapidly losing its ability to meet our national security needs." After detailing problems relating to the skyrocketing costs, lack of accountability, unrealistic goals, a flawed concept of operations, the perils of designing a warship around stealth, as well as the failure of the Advanced Gun System, Fredenburg concludes:
"The Zumwalt is an unmitigated disaster. Clearly it is not a good fit as a frontline warship. With its guns neutered, its role as a primary anti-submarine-warfare asset in question, its anti-air-warfare capabilities inferior to those of our current workhorse, the Arleigh Burke-class destroyers, and its stealth not nearly as advantageous as advertised, the Zumwalt seems to be a ship without a mission."
https://en.wikipedia.org/wiki/Zumwalt-class_destroyer#Controversy