A Whitefish man who initially faced a state felony charge for possession of explosives pleaded guilty to possession of a firearm without a serial number in federal court in Missoula on Jan. 20.

Andrew Benningfield, 37, was arrested Aug. 10, 2007, after two police officers caught him outside the back door of the Whitefish Police Department with a home-made explosive device. He was charged with disorderly conduct and criminal mischief.

An explosives enforcement officer with the Bureau of Alcohol, Tobacco and Firearms X-rayed and analyzed the device two days after Benningfield was arrested and concluded it was a “directional mine.”

The device consisted of a metal pipe with a cap on one end. Inside, a .30-30 shell was held in place with a piece of rubber hose, and a broken drill bit was routed through a hole in the metal cap to strike the firing pin.

Benningfield’s case was transferred to federal court, and he was charged in January 2008 with possession of a bomb by a person who had been committed to a mental institution. He pleaded not guilty to that charge.

Later, the explosive device was re-designated as a “firearm.” Personnel from BATF were prepared to testify that the device “was in fact a firearm capable of firing an ammunition cartridge,” according to the Assistant U.S. Attorney for the District of Montana.

Benningfield faces up to 10 years in prison, a $10,000 fine and supervised release. Sentencing is scheduled for March 27.