BEND, Ore. — The family of an Oregon man killed when a cannon shell exploded in his World War II-era tank has filed a $12.8 million lawsuit.

Steve Preston's family is suing Chuck Hegele, the contractor who supplied powder for the shell, The Bulletin reported .

Preston, 51, and his assistant Austin Lee, 22, were killed inside Preston's 1944 M-18 Hellcat, a tank destroyer, at a gun range outside of Bend in 2015. They were attempting to fire a round when it exploded. Lee died instantly and Preston survived for 27 minutes.

Tim Williams, the attorney representing Preston's family said one of the reasons for the high amount the lawsuit seeks is because Preston, knew he was going to die during the nearly half-hour he lived after the explosion.

Preston contracted with Hegele to supply and supervise use of ammunition for a firing demonstration being filmed for the Flying Heritage & Combat Armor Museum in Everett, Washington, the lawsuit said. Hegele used old propellant, the lawsuit said.

Hegele told the Bend newspaper Preston is responsible for his own death. He said Preston made mistakes, including overloading the shell.

"I told him, 'If you put one more ounce in there, you're going to blow yourself up," Hegele said. "He put 8 more ounces in."

Hegele said his insurance companies will likely settle, but for far less than $12.8 million.

"Steve loved attention," Hegele said. "That's what killed him."

Lee's estate filed a wrongful death lawsuit in February against Hegele and others.

In 2016, Deschutes County District Attorney John Hummel announced he wouldn't bring charges. "We followed the evidence where it led, and at the end of the day, we do not know the cause of this explosion," he said at the time.