From space, maybe. A railgun on the surface of Earth that was trying to slow down a piece of space junk would, by necessity, be aimed at a low angle. Getting a projectile a couple hundred kilometers up while launching at such angle would make this railgun be something between a window-shattering nuisance and a weapon of mass destruction, depending on muzzle velocity and the size of the projectile.

The problem is, of course, the atmosphere. That thick soup of gas that's at its densest near the surface, and has the annoying tendency of engulfing hypersonic projectiles in a thick ball of screaming-hot plasma.