Trumna
The Trumna is an Orokin-Era weapon created by the Entrati, a fully automatic rifle chambered in 27x90mm.Codex Entry:
"An ancient weapon designed by the Entrati. Primary fire siphons life essence from the target to fuel a devastating alt fire. A heavy, oversized automatic rifle with withering fire that delivers rapid heat damage. Alt fire unleashes an arcing projectile that ricochets off surfaces and enemies, exploding every impact."
Credits: Warframe By Digital Extremes