jblomenberg16
Grandmaster
Here's a partial explanation for the flame:
"The flames are from pieces of the projectile disintegrating; the 7-pound slug is jammed so firmly between the rails that when it's fired, pieces shear off and ignite in the air."
Navy Tests 32-Megajoule Railgun | Popular Science
http://youtu.be/i1q_rRicAwI
That makes sense. I would venture to say that as this gets closer to production that will be something they address.