U.S. Attorney Chris Thyer said he was pleased with the court's decision.
"The United States understands and accepts the reasons for the reversal on the machine gun and sentencing issues and will prepare for the resentencing hearing," Thyer said in a statement. "The affirmation of the jury's verdict on the counts of conviction puts to rest any questions of the defendant's guilt, especially regarding his role in the 2009 bombing of Dr. Trent Pierce."
Online court records didn't list a new sentencing date for Mann as of Thursday.
"We're hopeful, obviously, that he will be able to get some relief from a life sentence," one of Mann's lawyers, Blake Hendrix, said.
Hendrix also said he anticipates asking the appeals court to rehear the case and reconsider the rulings that were unfavorable to Mann.
Federal prisons records show Mann is serving a life sentence at the U.S. Penitentiary-Canaan, about 20 miles east of Scranton, Pa.
Associated Press writer Jill Bleed contributed to this report.
Follow Jeannie Nuss at http://twitter.com/jeannienuss