This is my own creation/invention it would go in the BattleTech universe.
The Guass rifle is a set of electromagnets that propel a solid titanium shell at the target.
What is battletech you ask?:
It is the 31st century and man kind is once again at war.
The battlefields of the future are dominated by huge robotic war machines known as Battlemechs.
Piloting these awesome weapons of war are men and women, the elite of the elite, knowing that each battle could be thier last.