Earlier quoted context omitted.
One important difference is heat management. Electric weapons are super neat. Their specs can put the projectile very kenetic, they can uitilize more exotic energy sources, etc. However, in terms of a man portable gun, they just really don't have the specs needed. Sure, we can make them more ruggeded and more effective at lower KE output. But a major issue for a man portable gun is heat. Heat causes expansions and af…
We have much better engineering tools today, so why would it take decades ?
The weapons we have today are very well engineered (cheap, reliable, understood tolerances/ranges, etc). As such, where railgun tech will be used is in limited cases as compared to the well developed cheamically launched projectiles. That means that there are less cases where the railgun can be used and then learned from. Especially with weapons, you need real life testing in order to understand the engineering issues, as lab testing is generally forbidden due to loss of human life. Hunting deer and boars will only give you so much. Fortunately, we humans don't go to War too often these days (though this is very debatable to a lot of real people). Unfortunately for railgun engineers, that means there is not a lot of real world testing in the panic that is a battle.