Isn't Maxim's heavy machine gun patented? Why did Germany and the Republic of China wreak havoc on imitations, while Hotchkiss did not dare to use water cooling to dissipate heat, but used air to diss

Isn't Maxim's heavy machine gun patented? Why did Germany and the Republic of China wreak havoc on imitations, while Hotchkiss did not dare to use water cooling to dissipate heat, but used air to dissipate heat? Maxim heavy machine gun is the earliest weapon to realize continuous shooting, which was patented in 1884. You know, once it becomes a patent, it means openness. Once it is made public, there will be a large number of researchers. Moreover, the earliest Maxim heavy machine gun was water-cooled. As a heat dissipation holster, it needed a lot of water, which increased its own weight and made it inconvenient to go into battle lightly. So it was improved by Hotchkiss in less than 10 years, and patents encouraged innovation. After using gas to dissipate heat, it no longer retains the attributes of the original patent. It has been nearly 30 years since the Republic of China applied for a patent. The longest protection period of invention patent in the world is 20 years, and the patent has already expired. Moreover, China did not recognize patent protection in the early days, and the first patent law in China was promulgated only in the 1980s. Germany has a long history of ambition, and weapons are his favorite. Even if there is a patent, he will be desperate to copy it. After this incident, people also learned a lesson from it. Later, no one used patents to protect the cutting-edge technology of national defense. Imagine, when your country and nation are in danger, who will practice the patent agreement? At present, there is no valuable information on the list of national defense science and technology awards in China, and everything from principle to inventor has been replaced by "secret".