Steering
A rail gun round isn't going to be steerable. Changing the direction of a round going that fast would be incredibly hard. To even try means building a system into the projectile that can take the acceleration and the EM field, and still survive. The best they can hope for is the ability to nudge the round a bit just before it hits a target if it has slowed down enough.
One of the premises of magneforming is that the material is smacked into the form so fast that it can't deflect. An example that is used to explain the process is taking a long metal bar, putting the end against a concrete wall and trying to push it through. The bar will bend. Launch that same bar at a high velocity and you have a "long bar penetrator" that will pound its way to the other side with very little bending. A rail gun round will direct its energy in the direction of travel and won't be able to spread out and dissipate that energy over a very wide area before it's passed through something. With firearms it's often called knock down power. Small high velocity rounds will often pass right through the target where a bigger round going slower (same total kinetic energy) will knock the target down and do far more damage. How often is it more optimum to put a bunch of holes into the side of something over stoving the whole thing in?
Biting the hand that feeds IT
