Vu Thi Diep, 33, was found guilty of "illegal manufacture, possession, transport, use, or appropriation of military weapons or devices."
Duong Minh Tuan, 31, also got nine years on the same charges, and 15 others who were members of the smuggling ring, got six months to seven years.
In 2019 Diep and her husband were found guilty of illegal weapons sales by a court in Cu Chi District in Ho Chi Minh City.
She got a three-year sentence, which however was suspended since she had a young child.
But she continued to establish links with people to smuggle weapons from Cambodia to Vietnam.
One of them was Tuan.
In August 2022 the Kien Giang police caught Tuan red-handed with methamphetamine at a motel in Rach Gia City.
A search of his house turned up equipment required to make firearms.
Tuan admitted he knew how to make guns, and along with some others made 15 guns that fired rubber bullets between May and August that year.
The ammunition was provided by a husband and wife couple in Rach Gia, Cao Van Hoai and Vo Ngoc Tram.
Tuan sold eight guns at VND1-5.5 million ($42-231) each and around 50 bullets in Kien Giang and the neighboring provinces of An Giang and Ca Mau.
He also gifted a gun to a customer.
The police searched the house of Hoai and Tram and found around 70 guns and 239 bullets.
They in turn fingered Diep, telling the officers she had supplied them the guns and bullets.
Further investigations resulted in the arrest of Diep in HCMC and her three henchmen in Binh Duong and Khanh Hoa provinces.
A search of Diep's warehouse in Nha Trang in Khanh Hoa turned up 229 guns, six bullets and some tools and equipment.
Investigators said that in 2022 Diep had supplied to Hoai and Tram 400 guns, 1,300 rubber bullets and 1,300 pressurized gas canisters.
Hoai and Tram sold 40 of the guns to their customers and 190 others to Diep's.