Breacher missiles are so named because they use gravitics to breach gravitic shields.
They may approach at up to 70% CEE, but that doesn't prevent a good ship from swatting them.
The Staff of Unyielding Order has just been struck in the primary annie plant by a breacher moving at 99.682% CEE. . . an improbably high speed, though clearly not impossibly high.
Staff of Unyielding:
Sorry, sir. I didn't get the license plate.
What appears impossible is that the breacher removed and safely scattered the neutronium, and flew off unharmed.