PITTSBURGH—A Pittsburgh-area man has been sentenced to nearly 16 years in prison for teaching an FBI informant how to build a nail bomb that the defendant believed was meant to kill a federal witness.

Michael Steven Cech (chek), of McKees Rocks, pleaded guilty in September to trading a .45-caliber handgun and $300 in exchange for providing the equipment and instructions needed to build the bomb.

He was sentenced to 15 years, eight months in prison on Wednesday after federal prosecutors played video recordings in May during which the 42-year-old Pittsburgh-area man believed he was teaching someone how to blow up a federal drug trial witness.

As part of his plea bargain, the government agreed not to recommend a sentence of more than 20 years in prison.