Railguns show the gap between invention and fielding

Which future defence technologies are most likely to become operational?

Many may eventually work, but their fielding dates are highly uncertain; railguns have had working concepts since 1917 without becoming routine weapons.

Many familiar future-weapon concepts may eventually enter service. The difficult question is whether that happens in a decade or a century. A French inventor is credited here with producing a working railgun model in 1917, long before the weapon became a modern procurement headline. The early model illustrates how a feasible principle can precede operational service by more than a century.