Hamilton, Montana – A Hamilton man with multiple previous felony convictions has been sentenced to two years in federal prison after a jury found him guilty of unlawfully possessing a firearm, federal prosecutors announced.
Shawn Ryan Cowan, 46, received a sentence of 24 months in prison, followed by three years of supervised release. U.S. District Judge Donald W. Molloy presided over the case.
Cowan was convicted following a one-day jury trial on April 13, 2026. Acting U.S. Attorney Mark Steger Smith announced the sentence.
According to evidence presented by the government in court documents and during the trial, investigators learned that Cowan was allegedly keeping a collection of firearms inside his Hamilton home despite his status as a convicted felon.
A tip provided to law enforcement led investigators to seek a search warrant for the residence.
Investigators discover firearms and ammunition
During the search, authorities found 10 firearms as well as various kinds of ammunition.
The weapons included a Ruger SR 22 .22 caliber pistol, a Raven Arms P25 .25 caliber pistol and a F.LLI Pietta Fabrica D’Armi Big Bore Rough Rider .357 caliber revolver.
Investigators also discovered two rifles, including a Derya Arms TM22 A 18 .22 caliber rifle and a Marlin Firearms Co. 20 .22 caliber rifle.
Several additional revolvers were recovered. They included a High Standard Sentinel .22 caliber revolver, a North American Arms NAA22 .22 caliber revolver, a Smith & Wesson 18 .22 caliber revolver, and a Heritage Mfg. Inc. Rough Rider .22 caliber revolver.
Authorities also found a Derya Arms VRPA40 12-gauge shotgun.
Cowan was prohibited from legally possessing firearms because of his criminal history. Prosecutors said he had previously been convicted in Montana of aggravated kidnapping, burglary and possession of dangerous drugs. His criminal history also required him to register as a violent offender for life.
According to federal authorities, Cowan became belligerent with agents when he was arrested. He acknowledged that he was “technically a felon,” but maintained that he possessed firearms because he believed his earlier conviction had been fraudulently obtained by county officials.
The federal case ultimately went before a jury, which found Cowan guilty of unlawfully possessing a firearm after the one day trial in April.
Following his 24 month prison term, Cowan will remain under federal supervision for another three years.
The U.S. Attorney’s Office prosecuted the case. The Bureau of Alcohol, Tobacco, Firearms and Explosives and the Ravalli County Sheriff’s Office were responsible for the investigation that led to Cowan’s prosecution and conviction.
