From: xxxxxx@shadowgard.com
>
> railguns use (if I recall correctly) JxB forces. They require a steady
> *strong* magnetic field (vertical if the gun is aimed parallel to the
> ground).

No, they don't require a *steady* magnetic field; an electromagnet that only runs during the period the projectile is accelerating will do the job, in fact in principle the magnetic field can be generated by the accelerator current.

Both railguns and gauss guns will generate large signatures if unshielded, but there's no technical requirement that they be unshielded other than the gun nozzle itself.