The GX-15 "Starbolt" concussion missile was designed by the Rebel Alliance following the Battle of Hoth and was in fact an armor-piercing warhead.
It had a pseudointelligent guidance system which was capable of identifying and locking onto targets by simple verbal commands alone. Once it reached its target, it directed a concussive energy charge which was capable of blasting straight through a garrison wall or disable and, on some occasions, outright destroy an Imperial AT-AT with a well placed shot.