An alleged member of the neo-Nazi group Atomwaffen Division pleaded not guilty to federal gun charges on Thursday, the Fort Worth Star-Telegram reports. Aiden Bruce-Umbaugh, 23, was charged with possession of a firearm by an unlawful user of a controlled substance earlier this week, and could face up to 10 years in prison if convicted. Bruce-Umbaugh, originally from Washington, was arrested earlier this month after authorities found AR-15 rifle, two AK-47 rifles, a Sig Sauer 9 mm pistol, and at least 1,500 rounds of ammunition during a traffic stop that followed an FBI investigation. Officials also found marijuana and THC oil in the car with Bruce-Umbaugh, who was allegedly traveling from Washington to Houston with Atomwaffen member Kaleb Cole. Cole was driving the car, but didn't get charged. Bruce-Umbaugh eventually told authorities that the weapons, marijuana and THC belonged to him after he initially denied having anything illegal in the car.