China has been using gunpowder for military purposes since the Tang Dynasty*, and in the Southern Song Dynasty, in order to deal with the Mongol Empire that rose in the north, gunpowder weapons were carried forward, and at this time the body weapon assault rifle had been invented. However, due to the lack of power in the gunpowder formula and the variety of materials used to make firearms, firearms in this period could only be used as auxiliary weapons.

At that time, in order to fight for control of South China, Zhu Yuanzhang fought with Chen Youliang in the middle reaches of the Yangtze River and Zhang Shicheng in the lower reaches, because Zhu Yuanzhang was the weakest at that time, so he had no choice but to develop a large number of new weapons such as firearms.

Zhu Yuanzhang used firearms to defeat various peasant separatist forces, drove out the Mongols and established the Ming Dynasty. The establishment of the Ming Dynasty brought China's feudal society to a new historical period. At that time, the social economy was very prosperous, agriculture, handicrafts and commerce were extremely developed, overseas trade was very active, new productive forces and production relations were in a state of embryonic state, capitalist factors began to sprout, and there was a marked turn for the better in scientific and technological progress.

All these new progressive factors provided the material and technical basis for the development of weapons, especially gunpowder and firearms, in the Ming Dynasty. In addition, in the Ming Dynasty, the north was harassed by the nomadic tribe aristocratic rulers for a long time, and the southeast coast was often invaded by the Japanese invaders, so in order to consolidate the border defense and resist the invasion of foreign tribes, the rulers of the Ming Dynasty attached great importance to the country's armament, and paid special attention to gunpowder and firearms. Under such a historical background, the gunpowder and artillery of the Ming Dynasty developed rapidly, and there was a heyday in the history of gunpowder and artillery in China.

From the beginning of the Ming Dynasty, firearms were added to the combat sequence as the main branch of the Ming army, and even the Shenji Battalion of the all-firearms unit appeared in the Yongle period. During this period, after hundreds of years of exploration from the Song Dynasty to the Ming Dynasty, craftsmen could already use metal as the main material for firearms, and various body weapons emerged in an endless stream, making great contributions to Zhu Yuanzhang's ability to occupy the whole country.

After the establishment of the Ming Dynasty, the development of firearms in the imperial court did not stop, and in the middle of the Ming Dynasty, various types of weapons already had the basic characteristics of modern firearms, such as the fire gun has a lookout mountain and a trigger, and the artillery has a gun ear and gun carriage.

During the Wanli period of the Ming Dynasty, the Ming army in Guangdong salvaged the Dutch merchant ship that sank in the Pearl River Bay, and found that the artillery on it was much more advanced than the artillery they used, and immediately reported to the imperial court to start copying. During this period, the scientific and technological strength of the Ming Dynasty was not much worse than that of the West, so this Western cannon was quickly imitated, and the imperial court named it Hongyi Cannon, and it was this imitation of Hongyi Cannon that killed Nurhachi in Ningyuan City, Liaodong.

The Hongyi cannon is very powerful, but the imitation artillery of the Ming Dynasty is still not as powerful as the original, and there is no way to increase the power and range, so the thickness of the cannon can only be increased, so that the most important mobility of the artillery is gone.

This is also a helpless thing, the appearance of the gun is very easy to imitate, but the specific casting method and the manufacture of raw materials cannot be learned by imitation. The method of casting cannons in the Ming Dynasty was still the mud fan method, that is, a process developed from the sand turning method used in ancient China.

The clay fan method was used in the Western Zhou Dynasty, when it was mainly used to make bronzes. The principle of the mud model method is very simple, first use a fine basket to sieve the white mud, and remove stones and debris. Then the evenly mixed clay is beaten into flat clay sheets, and after the clay flakes are half dry, several large pieces of mud are made into several large pieces of mud according to the shape of the cast artillery, and then dried, or baked over a slight fire, and the defects on the inner surface of the fan are trimmed and mended, so that they are as smooth as possible, which becomes the outer model used in casting.

Then the inner fan is made with the same process, and the outer fan is divided into several parts, and the inner fan is a whole. However, it is smaller than the outer fan, and the size difference between it and the outer fan is the thickness of the cannon. It is also to wait until the inside and outside are all dry, put the inner fan upside down on the base, and then place the outer fan around the inner fan. After the outer fan is closed, seal the outer fan with cement, wait until the cement is dry, and then cover the closed fan cover above, and leave at least one pouring hole on the fan cover.

Then it is casting, the melted bronze solution is injected along the pouring hole, and after the molten iron is cooled, the outer fan and the inner fan are broken, and the cast cannon is taken out, which is the production process of the Hongyi cannon.

This process cannot be said to be bad, the mud fan process is simple, and the raw materials can be taken locally, which is suitable for large-scale production. However, it is possible to make bronze using the clay method, but it is not possible to use pig iron at higher temperatures. Because the mud fan also contains bubbles in how to dry in the shade, when the molten iron with a temperature of up to 1,000 degrees is poured into the mud fan, the bubbles will expand, so that bubbles will appear inside the cast gun body, which has a lot of impact on the service life and power of the gun.

The ductility of pig iron is not as good as bronze, and the process inevitably forms sand holes, in order to prevent explosions, domestic cannons are very heavy, so there is a thousand catties of cannons.

There is no reason for the original artillery salvaged from the sea, of course, it is not that the Western production process is more advanced, but the West has changed the mud model method to the lost wax method, which greatly reduces the formation of bubbles in the gun body.

Ma Cheng will not know the Western lost wax method, but he will have a simpler and more suitable process for China's national conditions, which is the iron model method.

The iron model method is also called the iron mold casting cannon method, and the inventor is Gong Zhenlin in the late Qing Dynasty. Gong Zhenlin is a county magistrate in Jiaxing County, Zhejiang, and he originally had nothing to do with the arms industry, but he had a reputation for "being ingenious", and during the Opium War, he was transferred to the Ningbo military camp by Yu Qian, the governor of Liangjiang, to be responsible for casting cannons.

At that time, the Qing Dynasty was fighting against the Taiping army, and there was a lot of loss of artillery on the front line, and the demand was extremely high. After several experiments, Gong Zhenlin finally invented the iron mold casting method.

The iron mold casting method is similar to the clay method, and the wrought iron is first used to make a hard mold of suitable size. When casting the gun, first brush the inside of each petal of the iron mold with two layers of slurry. The first layer of slurry is made of fine rice husk ash and fine sand mud; The second layer of slurry is made of fine kiln coal and water. Then, the two petals are combined, tightened with iron hoops, baked, and continuously continued, and finally the molten metal is cast. After pouring enough molten liquid and cooling and forming, the iron mold is immediately peeled off according to the order of the mold flaps, like peeling off the bamboo shoot shell, and the gun body is gradually exposed, and then the mud embryo in the gun core is removed, and the chamber is naturally smooth.

Compared with the traditional clay mold casting gun, the advantage of the iron mold casting gun is that the cast gun body is of good quality, and the inner and outer surfaces are smooth, unlike the clay mold, which will make the gun body produce bubbles. In addition, because there is no need for hard work such as drying clay molds, the manufacturing speed is extremely fast and is not affected by the climate. Because the mold can be reused, the production speed is fast, the output is large, and the cost can be very low. The greater significance lies in standardized manufacturing. Standardizing the mass production of products that are almost identical in appearance and performance is essential for artillery.

Ma Cheng's method is more advanced than Gong Zhenlin's, Ma Cheng has seen a lot of crossings in later generations, and decided to use the self-tightening method used in the Civil War in later generations.

The first step is to make an exterior fan like Gong Zhenlin. The traditional clay mold casting method is then used to cast the iron inner fan, which can be used to cast the cannon. Because the inner fan is also made of iron, the interior is hollow, and there are pipes at each end for water intake and drainage.

This time, the gun body did not use pig iron, but used mild steel. When the molten metal is poured into the mold, the molten metal begins to cool slowly, and the water in the inner mold comes in handy, the molten metal near the inner mold is the first to cool and condense into steel under the action of water, while the molten metal in the outer layer cools slowly.

Because of the principle of thermal expansion and cold contraction, after the whole casting is cooled, the cooling part of the outer layer will tightly clamp the inner layer to cool the part first, so that the whole casting will produce an inward tightening force, which is the force that makes the barrel able to withstand greater chamber pressure. This method of controlled cooling of the inner mold can have the effect of "self-tightening of the body tube".

The service life of the body tube through the self-tightening process of the body tube is greatly extended, and the thickness of the body tube can be greatly reduced, the weight is reduced, and the mobility of the gun is increased.

Of course, this is just a method that Ma Cheng came up with, and Song Yingxing still needs to actually operate what to do, and Ma Cheng does not have the ability to do it.

At that time, Ma Cheng handed over the drawings and the casting method he wrote to Song Yingxing, and Song Yingxing looked at it and didn't have anything, but said that he wanted to study it first. This research has been studied for three months, and Ma Cheng has already given up on whether he can produce qualified cannons, but he didn't expect Song Yingxing to send news at this time, asking Ma Cheng to come and cast cannons.

Ma Cheng came to the cannon casting workshop and saw that Song Yingxing commanded the workers to be busy, this old guy has not gained a lot of weight for a few months, Ma Cheng in order to satisfy the old guy, in terms of material conditions as much as possible to satisfy the old guy, in addition to sending Song Yingxing's two sons to Qian Qianyi as apprentices, he also spent five hundred taels of silver to redeem a Qingqi person from the hook fence and handed it over to the old guy Song Yingxing to spoil.

However, there is a reward for paying, and the reward now is that Song Yingxing finally made an artillery for Ma Cheng.

Although Ma Cheng called Song Yingxing an old guy in his heart, he didn't dare to be disrespectful on the surface, because this era pays attention to the prince of heaven and earth, if you don't respect your teacher, you basically can't mix it in society.

Ma Cheng still has lofty ideals, so although he scolded Song Yingxing in his heart, he still bowed forward and saluted: "Apprentice Ma Cheng, meet the teacher!"

Although it is December now, but because this is a cannon casting workshop, the temperature inside is still very high, Song Yingxing wiped the sweat on his face, and said after seeing Ma Cheng: "Zhonghe and you are here, this time the division finally lived up to expectations, and made your iron mold casting cannon method out, today is the first casting, so let you take a look!"

Ma Cheng listened to Song Yingxing's words and slapped his ass: "The teacher is really talented, the apprentice is just an idea, I didn't think about it at all, I didn't expect the teacher to succeed, the apprentice is really admired!"

Song Yingxing waved his hand to interrupt Ma Cheng's fart: "Okay, now wait a while, the most important casting will start in a while!"