The M18 was copied by the People's Republic of China as the Type 36.
The U.S. had provided Nationalist China the blueprints for the weapon.
When the communist Chinese seized the factory, they took advantage of the facilities and blueprints to make their own copy of the weapon.
China provided the communist Vietnamese the Type 36 in 1963 for use in the Vietnam War.
Tanzania was also a user of the Type 36.
In a strange twist, the Chinese version of the M18 can fire both U.S. and Chinese manufactured ammunition, but the U.S. made M18s cannot fire Chinese ammunition.
This was done deliberately by increasing the bore of their weapons and ammunition by 1 mm, making their munitions too large for use by NATO weapons in the event of capture, but not vice versa.

The French army also used M18 guns during the First Indochina War, Algerian War and French intervention in Tchad in 1970.

As late as 1984, the M18 57 mm recoilless rifle was still being produced under license in Brazil by Hydroar in São Paulo.

At least one gun was used by the Syrian National Army during the Turkish military operation in Afrin in Northern Syria.
The M18 was copied by the People's Republic of China as the Type 36. The U.S. had provided Nationalist China the blueprints for the weapon. When the communist Chinese seized the factory, they took advantage of the facilities and blueprints to make their own copy of the weapon. China provided the communist Vietnamese the Type 36 in 1963 for use in the Vietnam War. Tanzania was also a user of the Type 36. In a strange twist, the Chinese version of the M18 can fire both U.S. and Chinese manufactured ammunition, but the U.S. made M18s cannot fire Chinese ammunition. This was done deliberately by increasing the bore of their weapons and ammunition by 1 mm, making their munitions too large for use by NATO weapons in the event of capture, but not vice versa.
The French army also used M18 guns during the First Indochina War, Algerian War and French intervention in Tchad in 1970.
As late as 1984, the M18 57 mm recoilless rifle was still being produced under license in Brazil by Hydroar in São Paulo.
At least one gun was used by the Syrian National Army during the Turkish military operation in Afrin in Northern Syria.
M18 recoilless rifle