He became president of the Deterrence Research Corporation (or DRC), the world's foremost independent weapons manufacturing firm. As an arms expert, Magnum battled Spider-Man and the Punisher. Magnum surprisingly survived after the Punisher exposed him to chemical weapons. Then, he seemingly fell to his death after a battle with Luke Cage. However, Magnum was rescued by Apocalypse and granted superhuman powers which Magnum dubbed his "Magnum Force. His powers included superhuman strength and geologically-based powers to cause earthquakes and sense disruptions in the Earth.
Tyrannus and his allies, They Who Wield Power, secretly gave Magnum technology which enhanced his superhuman strength and the power to focus vast amounts of energy so as to trigger earthquakes. Magnum next threatened to create earthquakes to sink Japan unless he was named the nation's ruler. His plan was foiled by an assault by the X-Men and Sunfire on Magnum's Kuril Islands headquarters. Banshee disrupted Magnum's earthquake beam, but suffered a long-term loss of his own sonic powers in the process.
Magnum later became an adversary of Deathlok.
Later, Magnum's efforts to regain control of his power and destroy a floating resort using a stolen experimental seismic cannon were foiled by the combined efforts of the Avengers and future Avenger Triathlon. His own powers opened a fissure beneath him, seemingly sending him falling to his doom.