( CNN ) -- A Michigan militia leader and his son pleaded guilty Thursday to federal gun charges two days after a federal judge in Detroit dropped the more serious charges of sedition and conspiracy to use weapons of mass destruction against the government . David Stone , Sr. , 47 , and his son Joshua Stone , 23 , members of the Hutaree Militia , face up to 10 years in prison and a fine of up to $ 250,000 after admitting to possessing illegal automatic firearms . Both have already spent two years in prison . `` We are gratified that these felony convictions mean that these defendants will never be permitted to possess firearms again , '' said U.S. Attorney Barbara McQuade . Federal authorities accused nine members of the `` Christian warrior '' militia of homegrown terrorism . The FBI planted a secret informant and FBI agent in the militia in 2008 to record the activities of the group . The video and audio recordings became the crux of the federal case , including clips of the elder Stone making anti-government statements and remarks about killing police officers . But in a trial that began in early February , federal District Judge Victoria Roberts said she did not find that the government 's evidence sufficiently proved that the Hutaree militia had planned a conspiracy against the government . `` The court 's order dismissing the more serious charges in this case was disappointing , but it does not shake our commitment to dismantling groups who would harm our citizens and law enforcement officers , and these efforts will continue , '' McQuade said . The move cleared several of the original nine defendants of all charges . The Stones `` admitted that they possessed machine guns , specifically a Bushmaster .223 caliber rifle and a Double Star Corp. .223 caliber rifle respectively , knowing that the firearms would shoot , and were designed to shoot , automatically more than one shot , without manual reloading , by a single function of the trigger , '' the U.S. attorney 's office said . Roberts , in her 28-page ruling dismissing the more serious charges , said the `` government 's case is built largely of circumstantial evidence . '' `` While this evidence could certainly lead a rational fact finder to conclude that 'something fishy ' was going on , it does not prove beyond a reasonable doubt that defendants reached a concrete agreement to forcibly oppose the United States government , '' Roberts said . `` Pick a sentence here , pick a sentence there -- the ( remarks were ) taken out of context , '' a defense attorney for one of the cleared militia members said . `` We always said it was a First Amendment and Second Amendment case , and that 's what it ended up being , '' added attorney Michael Rataj , whose client , Tina Stone , is the wife of the elder Stone . The Hutaree militia members cleared of all charges are Tina Stone , 46 ; David Stone , Jr. , 22 , another son of the elder Stone ; Thomas Piatek , 48 ; Michael Meeks , 40 ; and Kristopher Sickles , 29 . Defendant Joshua Clough , 30 , awaits his sentence after pleading guilty to a weapons charge in December . Another defendant , Jacob Ward , 35 , will be tried separately . `` I did n't figure we were doing anything wrong -- in the lines of going out there and doing the trainings -- to me it was basically fun , '' Tina Stone said Wednesday . `` I 'm worried for my husband and son . I guess I will be able to live my life a little easier once they 're home . ''
David Stone , Sr. , and his son Joshua Stone face up to 10 years in prison for gun charges . The judge dropped more serious charges against the Hutaree Militia members . `` We are gratified '' the Stones will never possess guns again , the prosecutor says .