Chapter 102: Cannon Casting (Part 1)

“The first meeting of the Cannon Production Leading Group now begins!”

In the simple but spacious office of the machinery factory, a blackboard was set up. Led by the head of the mechanical group, Zhan Wuya, the weapons enthusiasts gathered together. The atmosphere was extremely enthusiastic, and everyone was heatedly discussing which type of cannon to produce.

“Now, let me first introduce the attendees.” Zhan Wuya introduced everyone participating in the meeting. The main backbone of the mechanical group, such as Wang Luobin, Jiang Ye, and Xiao Bailang, went without saying. There were also some people who didn’t know much about machinery but were weapons enthusiasts. This included Zhang Bolin, who always had “cannons, more cannons” on his lips and had repeatedly proclaimed himself “General of the Artillery”; Wang Ruixiang, who liked to brandish an axe; Li Yunxing, who had served as the structural designer and on-site construction supervisor for the mechanical crossbow; Bai Yu, who had a background in weapons design and engineering, and armored forces command… and finally, comrade Lin Shenhe, who had a wealth of practical experience.

The purpose of this meeting was not to arrange production, but to determine the technical route, so it should be called a “Technical Route Seminar.”

“Let’s not consider whether it’s better to build a 12-pounder mountain howitzer or a 92mm infantry gun for now. Let’s discuss it from the perspective of practicality and manufacturing level,” Zhan Wuya set the tone for the discussion.

In terms of the machining capabilities possessed by the transmigrators, their processing level surpassed that of every civilization in this world. Now that they had also smelted steel, manufacturing simple steel rifled breech-loading cannons no longer presented a major technical challenge. Of course, there was a bottleneck with the spring for a recoil-operated cannon that was not easy to solve, but a carriage-recoil cannon was no problem at all.

Even the industrial level of the mid-19th century was sufficient to manufacture 15-inch caliber cannons, and even steel was not needed. Many super-caliber coastal cannons were cast iron cannons. The transmigrators had no ironclad cruisers to fight, so naturally, they didn’t need to build such a monstrous weapon.

What were the transmigrators’ needs? According to the staff group’s suggestion, it was mainly to equip the navy’s ships and forts with cannons.

“Naturally, it’s the rifled breech-loading cannon! It has too many advantages,” Li Yunxing was the first to speak.

According to the general idea, the farther the range of a cannon, the better. This created a problem. The increasing range of modern artillery is built on the foundation of modern sighting and fire control systems. This was impossible to achieve with the transmigrators’ industrial level, which did not exceed that of the late 19th century. Even if it were achieved with equipment brought from the 21st century, it would only be temporary.

A 24-pounder muzzle-loading heavy cannon had an effective range of no more than 900 meters. When such a cannon was mounted on a warship, its effective range was reduced by at least half due to stability issues. The British Royal Navy’s firing manual in the 18th and 19th centuries clearly stipulated that the maximum firing range of a 24-pounder long gun was 400 yards. Compared to the more numerous 32-pounder large-caliber short guns on warships, its effective range was already quite large. In actual combat, the distance at which warships engaged each other was often within 100 meters.

17th-century artillery certainly would not exceed this level. The purpose of the transmigrators’ naval breech-loading rifled cannons was not great power and long range, but rather rapid fire and weight reduction. Even if the range was increased due to rifling, it should be controlled within 2000 meters. Beyond this range, it might have some value on land, but for hitting moving point targets on the sea, it would be meaningless given the transmigrators’ fire control level. An excessive range would be a complete waste.

Since the range requirement was not high, the barrel of the cannon could be shortened to save weight and manufacturing costs.

Another advantage of using a breech-loading rifled cannon is that it uses pointed shells instead of round shot. Pointed shells are not only more stable in flight than round shot, but their shape—being elongated—allows for rearward development and weight adjustment for the same caliber. For the same weight, a pointed shell has a caliber of only about 70% of a round shot, and in terms of cross-sectional area, only 49%. This means that if both have the same muzzle velocity, the impact kinetic energy of the pointed shell is concentrated on half the cross-sectional area, and its energy density per unit is twice that of a round shot. Considering the low drag of the pointed shell, for the same weight of projectile, the armor-piercing power of a pointed shell is more than 3 times that of a round shot.

This also means that a 12-pounder pointed shell (caliber about 70mm) from a breech-loading rifled cannon, under the premise of using the same propellant and charge, will have a much longer effective range than a 12-pounder round shot, and its armor-piercing power will be equivalent to that of a 24-pounder round shot heavy cannon!

A 70mm breech-loading rifled cannon with a caliber length of 16-18 is a very small cannon, both in the past and in modern times. It weighs only about 400-500 kilograms and can be mounted on a 300-ton class sailing ship. If equipped with a recoil system, it can also be mounted on a 150-ton class small boat. This means that a medium-sized sailing ship equipped with a 70mm breech-loading cannon could completely compete with a first-rate ship of the line of the British Royal Navy during the golden age of sail.

Considering that its rate of fire is much greater than that of a 24-pounder muzzle-loading cannon, plus its advantage in effective range, the result is that a large sailing ship of the line would not only be helpless against it, but might even be “raped” in return for attempting to “rape.”

In other words, in the early 17th century, it would be completely sufficient to develop and produce such a small breech-loading cannon. It would already have an overwhelming advantage against any navy or pirate of the time.

“Then why don’t we just copy the Type 92 infantry gun?” someone said after hearing the explanation of the benefits of rifled breech-loading cannons. “The Type 92 infantry gun has a 75mm caliber and a maximum range of 2800 meters, which perfectly matches the performance described above. And the Type 92 gun only weighs 210 kilograms, which is smaller than the estimated 500 kilograms.”

“The problem with the Type 92 infantry gun is that its caliber length is too small, only 6, which results in a very low muzzle velocity. For a naval gun, the flatter the trajectory, the better. The Type 92 infantry gun is very good for the army.”

Wang Luobin proposed that this naval gun could adopt the structure of an Armstrong gun, which was a relatively mature and reliable breech-loading cannon with a relatively simple manufacturing process. Compared to previous types of breech-loading cannons and muzzle-loading rifled cannons, its distinctive feature was the introduction of a threaded breechblock and an obturator for breech-loading cannons. An Armstrong gun with its breechblock removed is very similar to a muzzle-loading cannon with its breech bored through, and the casting and machining processes for the barrel are also similar.

The disadvantage of the Armstrong gun was its early-type locking design, which was very complex, had low stability, and a high failure rate. The transmigrators would naturally not imitate it blindly. They could adopt a threaded breechblock, which did not have very high technical requirements. Basically, if they could make screws, they should be able to make it.

“Easier said than done,” Xiao Bailang poured a basin of cold water. “Who knows how to make a cannon? I think everyone has only read a few books, right? Not to mention the Type 92 infantry gun, which is made of ready-made seamless tubes. Where are we going to find such thick seamless tubes now?”

“Naturally, we’ll have to focus on casting cannons. After all, we don’t have a large forging press. If we were to use the deep drilling method, we would also have to manufacture special equipment,” Lin Shenhe said. “I have cast cannons in the United States, but they were all smoothbore cannons.”

Bai Yu said, “Actually, what I’m worried about is not whether we can make the cannons, but the ammunition problem. I agree with all the explanations of the benefits of breech-loading cannons, but there’s one point that doesn’t seem to be clear—the shells for breech-loading cannons are much harder to make than the cannons themselves. Solid armor-piercing shells are one thing, but what about high-explosive shells and shrapnel shells? How do we solve the metal extension process needed to manufacture pointed shells? And the fuzes for the shells are also a problem.”

Jiang Ye said, “There’s no problem with manufacturing the shell bodies. Our equipment can make them.”

“That just means we can make them, it doesn’t mean we can mass-produce them. A bullet production line has more than 30 dedicated machines. Shells require even more. Our industrial capacity is clearly not up to such a production line yet.”

“That’s right,” Zhan Wuya admitted. “And the materials might not pass the test either.” Whether the shell body is made by cold drawing or hot drawing, it requires special round bar stock and the manufacturing of special equipment. It’s not that the industrial department can’t do it, but it requires a complete industrial system to support it, otherwise the cost would be unimaginably high.

“No, the old-fashioned pointed shells weren’t that complicated,” Lin Shenhe said. “The shell bodies of early breech-loading shells were made of cast iron, coated with lead on the outside, and used a simple impact fuze. The shell was filled with black powder, and a black powder charge was used as the propellant. There was no cartridge case and no primer. It was also ignited with an igniter when fired. Most of the shells produced before 1890 belonged to this category. This type of shell is not suitable for the Type 92 infantry gun, but it’s absolutely no problem for an Armstrong gun.”

The reason why rifled cannon shells are coated with lead is to embed the shell body into the rifling. Cast iron or steel is too hard and would severely wear out the rifling. Therefore, even modern shells have a steel body (with a diameter smaller than the inner diameter of the rifling) and a copper driving band (with a slightly larger diameter that can be embedded in the rifling).

Wang Luobin said, “But there are some problems with lead coating. I remember that one of the reasons why the Armstrong gun was decommissioned after being briefly equipped and the British Empire went back to the muzzle-loading rifled cannon route was that when the Armstrong gun fired, due to the poor adhesion between the hot-dipped lead and the iron, torn lead fragments would scatter a short distance in front of the muzzle and cause injuries to their own soldiers.”

“I don’t think this is a particularly serious problem,” Lin Shenhe said. “I think the people in the mechanical department can figure out a way to solve it.”

“In addition, I personally think that smoothbore cannons can also be made,” Lin Shenhe said.

The process for making smoothbore cannons is simple, and the material requirements are not too high. If there is not enough steel, cast iron can be used directly. Early breech-loading rifled cannons like the Armstrong gun and smoothbore cannons are not much different in their casting process. Besides Lin Shenhe, no one had any experience in casting cannons. Using the relatively simple smoothbore cannon to practice and become familiar with the casting process was a good choice.

“I suggest that the commercial department list smoothbore cannons in the export commodity catalog. The Portuguese have now become the arms dealers of the Great Ming. We can’t let them earn this silver!”

[Note: The plot in this chapter regarding the casting of rifled cannons in the 17th century is all from SANJYSAN of the SB forum. The explanation of the Armstrong gun was provided by Wang Luobin himself.]