In custody Friday were Matthew Elshaug, 35, of Monroe, Casey Yount, 26, of Monroe, Levi Herz, 30, of Everett, and Raymond Baron, 52, of Marysville.
Elshaug is accused of breaking into the store and using a crowbar to steal 29 guns.
He and Yount then allegedly sold the guns to the other two men for drugs or cash.
Elshaug, Yount, and Herz were not allowed to possess firearms because of their criminal history, which includes burglary, theft, and crimes involving guns and drugs.
All four men are charged with conspiracy to traffic stolen firearms, according to the U.S. Attorney's Office. Some also face additional charges related to guns and drugs.
If convicted as charged, they face years in prison.
The case started at the Snohomish Police Department, where detectives made the initial arrests.
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