Japanese ship-mounted railgun successfully hits targets in test

From the article: "As railguns use electricity instead of explosive force, their projectiles are considered more durable and safer to store."

Yea, cost. It was supposed to be installed on the Zumwalt, with a guided 155mm cannon as an interim, also with the goal to be cheaper than missiles. Unfortunately both ended up being more expensive than missiles. Replacing the rails isn't something that can be done quickly or cheaply.

It is kinda comparable to hypersonic missiles in that it can penetrate air defense, but that is about the only overlap, the railgun is long range for a gun, but nothing compared to something like a hypersonic missile.

The issues were durability, fire rate, and well power.

I don’t know that the first two have changed significantly.

Nothing from what I understand. The issue is material science. The rails have a very short life unless fired at far less than full power.