Mecha and Mercenaries
Railgun of some sort
It plays beautiful music (with ferrous slugs at significant fractions of C)
This was the main weapon of a glorious-leader class experimental mech, it has a bright future in base defense, or getting strapped to someone’s shoulder as a “fuck off” main cannon, whichever.
“it’s basically a massive railgun that Thunders decided we could find a use for. So he chopped it off this giant fucking robot and insisted that we carry it home for him. we’re still trying to find a place to put the damn thing”—Zenon Kosakowski, crewman of the S.S. Aphetor