Ummar Yaqoob, 31, fired one of his “slam guns” through the living room window of a Bradford house in 2019, narrowly missing a man and his mother.
A police inquiry into the shooting uncovered the business, which he ran with then-girlfriend Kiran Bi Hussain.
At Bradford Crown Court, Hussain, 26, was jailed for more than six years.
Manufacture of the potentially deadly weapons had started in December 2018, the court heard.
The guns could be assembled from easily-obtained parts and Hussain, who believed she was in a loving relationship with Yaqoob, would order components, the court heard.
Yaqoob fired one of his weapons at a property on Agar Street on 31 March 2019, with the shot hitting the wall inches above where a woman had been sitting.
He believed the man inside the house had been
Judge Rose said he was satisfied that a number of the “slam guns” had been sold and noted that Yaqoob had been looking to expand his business by converting blank-firing guns into working weaponry.
Yaqoob, of Hill Top Mount, Leeds, was jailed for offences including the manufacture of the weapons and possession of a firearm with intent to cause fear of violence.
Hussain, of Ophelia Close, Bradford, was jailed for possession of a firearm with intent to cause fear of violence and her role in the manufacture of the guns.
Judge Rose, sentencing, said Hussain would not have been involved had she not been under the illusion that Yaqoob loved her and she believed herself to be in love with him.
“It is highly likely that you did naively believe yourself to be in a mutually loving relationship,” he told Hussain.