I'll point out that both railguns and lasers require considerable amounts of energy to do their jobs, and Cat is right, the rails undergo tremendous stress when they fire. Efforts are being made to reduce this, but so far as I understand it, the results are limited so far, simply because of the physics behind it. You need ferric to ferric conductive contact, so until we can come up with some sort of teflon-infused iron rails and/or slugs, well, problems arise.
Lasers, meanwhile, have massive efficiency issues. If we could find some way to recapture and use the waste photons that don't align properly, that could be improved, but barring that, we'd need a massive change in how we generate lasers to get a significant change in the power/output equation.
So to that end, Railguns are more power efficient than lasers, with much more of the juice put to use, as it were.
What's really interesting is that they've finally figured out how to sabot the railgun rounds which means depleted uranium, tungsten, explosive, and other special purpose rounds are finally on the menu. What's also interesting is that that rail barrel there seems to be round. If that's just aesthetics, it's a pity, if it's what I'm hoping for, which is rifling, that has other potential (and massive engineering problems I'm sure, but still).
Next up, force fields!
