Jackhammers are the Red Army's most powerful weapon. They double as both a starship and as an artillery battery. They can fire from orbit down onto unsuspecting victims or they can fire from the ground either at an advancing army or at an enemy ship in orbit.
Jackhammers destroy ships by firing a huge, concussive energy beam, rather than a projectile. Much like a pulse cannon. So rather than having a projectile ripping and cutting its way through, Jackhammers punch a hole through whatever it hits.
They also have the capability of pounding on the ground with giant pistons. This is primarily where they get the name Jackhammer.