SALT LAKE CITY (AP) — A Utah man has been sentenced to nearly three years in prison for illegally making and selling more than 1,400 machine-gun converter devices for AR-15-style rifles.

The Deseret News reports that Scott Ray Bishop was sentenced Thursday. He told U.S. District Judge Dee Benson that he thought his product was the same as bump stocks or trigger assemblies that are sold legally.

A jury in January found Bishop guilty of unlawfully engaging in the business of manufacturing machine guns and illegal possession and transfer of machine guns.

Benson called the case “troubling.” He said Bishop was seemingly unaware of how risky his endeavor was and that a lot of his clientele were people “we would not want converting anything into an automatic weapon.”