Black Corporation: Joseon

The decision was made to carve a large rifling inside the cannon, but the artisans fell into another dilemma.

“In which direction should we turn it?”

When they began discussing the rotation direction of the rifling, Hyang remarked, “When looking from the muzzle, why not make one rotate in the direction of a clock’s hand, and the other in the opposite direction?”

Upon hearing this, Choi Hae-san opened the ledger and began to calculate.

“Four types of rotations ranging from a half to two turns, two types of rotation directions, and needing to check the deviation… a minimum of five for each… that makes 40 in total. It’ll take some time.”

“We must strive.”

At Hyang’s words, the artisans in the room sighed lightly. However, no one complained. The work was hard, but surprisingly, they found relief in firing the cannon, and checking the results was somewhat enjoyable.

Of course, for Choi Hae-san and Lee Chun, who were sandwiched in the middle, it was more of a headache than fun.

In the ensuing tests, all 40 cannons showed better results than expected. All 40 were able to fire at least five times without any problems, and there was no significant decrease in power.

However, an unexpected result appeared during the analysis of the test results: the hit rate was higher than expected. Surprised by the unexpected result, Choi Hae-san suggested as he submitted his report.

“Even before, at a distance of 70 ‘bo’ (Korean measure of distance, 1 bo = 3.927m), if we fired 20 shots and hit 5, we considered ourselves lucky. But, in this test, all 40 cannons hit the target at a distance of 70 ‘bo’ (~275m). We need to research this!”

“I see. Let’s do it! Be ready.”

“Yes, Your Highness!”

As the excited Choi Hae-san left, Hyang clenched his fist, looking at his back.

“Yay! I’ve got it!”

To determine the cause of the unexpected result and to find a way to use it, Choi Hae-san, Lee Chun, and the artisans fired hundreds of bullets.

Through this process, the officials and artisans discovered several facts.

-The best performance was achieved when the rifling carved inside the cannon made one and a half turns.

-When the bullet was tightly bound to the fixed part and fired, it hit a target 500 ‘bo’ (approximately 600m) away. However, this means it hit the target, not a bullseye.

-However, this does not mean that the firing range of the cannon has increased. Regardless of the presence of rifling, 2 ‘don’ (approximately 7.5g) of blasting powder (mercury fulminate) can fire a 5 ‘don’ (approximately 17g) bullet up to 800 ‘bo’ (approximately 960m).

-At a distance of 500 ‘bo’, the bullet could not penetrate the iron plate used as a target. However, judging by the dent in the iron plate, it can be assumed that it can inflict considerable damage on the enemy.

-The direction of the rifling must be the same as the direction in which the cannon’s body and cap are tightened. If done in the opposite direction, the body and cap of the cannon loosen as more shots are fired.

“How about trying an experiment by increasing the amount of gunpowder?”

Choi Hae-san and Lee Chun showed enthusiasm, but Hyang shook his head. “There is a high chance of repeating the problems of the existing cannon.”

“Oh…”

“Instead, let’s systematize the results we have obtained.”

“Yes, Your Highness.”

Hyang, Choi Hae-san, and Lee Chun classified the results as follows.

-Maximum range: The farthest distance the bullet flew when firing with the prescribed gunpowder and bullet. There is almost no power in the bullet.

-Maximum effective range: The distance at which at least 30% accuracy can be expected when aiming and firing. However, it must retain enough power to inflict a certain level of damage on the target.

-Effective range: The maximum distance at which trained cannon soldiers can hit the target when aiming and firing.

According to the classification by Hyang, Choi Hae-san, and Lee Chun, the performance of the rifling cannon was a maximum range of 800 ‘bo’, maximum effective range of 350 ‘bo’, and an effective range of 250 ‘bo’.

While Hyang, Choi Hae-san, and Lee Chun were expressing considerable satisfaction with the results, the officials and artisans of the research institute were pondering how to solve the task that Hyang had given.

“‘Analyze the reason why the performance of the cannon suddenly improved.’…”

“Looking at the results of the tests we’ve done so far, the only reason for such a dramatic improvement in performance is the rotation of the rifling. But why did this result come out…”

“Yes, that’s the problem…”

The most likely culprit was ‘the rotating rifling’, but the officials and artisans couldn’t easily figure out what the rifling was doing.

While the officials and artisans were thinking, the military strategist’s arrow maker put forth his opinion.

“Wasn’t it the grooves that caused the bullet to spin?”

“Make the bullet spin? Could you explain further?”

The arrow maker elaborated in more detail, even using gestures.

“When the Europeans attach feathers to an arrow, they stick it on slightly skewed. Then the arrow spins like this when it leaves the bow. This makes the arrow fly straight. It’s also less affected by crosswinds.”

“Really?”

The craftsmen and officials thought it seemed plausible and began testing bullets of various sizes. The results confirmed that a bullet fitting into the protruding grooves of the spinning barrel improved accuracy.

All the knowledge and data obtained from the tests were documented and securely stored in a vault in the deepest part of Donggeubjeon (the main hall used for discussion of state affairs).

“This is a top-secret matter related to our national defense. Everyone must maintain utmost confidentiality.”

At Hyang’s warning, the officials and craftsmen answered in unison.

“We will bear it in mind!”

This confidential information was kept even during audits. Choi Hae-san did not reveal the part about the spinning grooves to Sejong while explaining the process of making the barrel.

Sejong only discovered this part after the audit was over. Choi Hae-san, who had an exclusive audience with Sejong, submitted a written report. After reading the report, Sejong nodded.

“I understand why the crown prince and the ministers were silent about it until the end. Then I must also follow suit. Chief Eunuch, bring the furnace.”

Sejong threw the report into the furnace and burned it.

Meanwhile, as Choi Hae-san was submitting the report to Sejong, Hyang muttered while looking at the related records.

“When the performance of the long barrel becomes known, it will inevitably leak out. Whether it’s captured during a battle, stolen, or sold for a bribe. And then they’ll gleefully replicate it. But by the time they understand the principle and attempt to improve it, we’ll be one step ahead. That’s why we’re doing all this.”

“Once again, you have created a truly marvelous weapon.”

“The barrels for the riflemen will be standardized with this armor-type long barrel.”

At Choi Hae-san’s statement, Hwang Hee tried to say something, but Sejong raised his hand to silence him.

“Hmm… if we gradually deploy it starting from the northern regions, it should be fine. Good! Review that plan.”

“Your majesty’s graciousness is boundless!”

“Your majesty’s graciousness is boundless!”

When Sejong made a positive decision about the production and deployment of the armor-type long barrel, Hyang, Choi Hae-san, and the related officials all bowed together and shouted, “Your majesty’s graciousness is boundless!”

“So, have you decided on the barrel?”

“No, there is one more type of barrel. It’s called a mounted barrel.”

“Oh?”

As Sejong showed interest, Choi Hae-san gestured. At Choi Hae-san’s signal, a soldier wearing blue armor entered.

“The color of the armor…”

“This is a newly developed type of armor we’ve been working on. I’ll explain later.”

“Is that so? Then proceed.”

At Sejong’s command, Choi Hae-san continued, “What I’m going to show you now is an armored mounted small barrel.”

As soon as Choi Hae-san finished speaking, the soldier opened the long leather pouch attached to his right waist and pulled out a silver barrel. He bent his arm to point the muzzle upward.

“I want to see it closely.”

“Yes, your majesty.”

At Sejong’s command, the soldier extended the barrel respectfully with both hands. Sejong’s gaze, examining the barrel he received from the soldier, stopped at the round metal tube in the middle of the barrel.

“There are six holes? Don’t tell me this barrel can shoot six shots?”

“That’s correct.”

“Huh!”

Surprised, Sejong turned to look at Hyang.

Seeing Sejong’s surprised eyes, Hyang answered with a smile, “It’s one of the results from the Area 51.”

‘Of course, its design already existed.’

The object in the soldier’s hand was a remodeled ‘Colt 1860 Army’, adjusted to the situation of the Joseon army. It was a device that Hyang had been preparing as a successor to the Kentucky rifle when he lived in the 21st century.

At Hyang’s answer, Sejong returned the barrel to the soldier, saying, “I want to see how it shoots.”

“Yes.”

In the ensuing demonstration, the warrior hit all six shots on a target board set up 30 paces (approximately 36 meters) away. The target board brought back by the artisans had six holes cleanly drilled through it. The artisans turned the board around. Behind the red cloth studded with lead pellets, iron plates were meticulously attached.

King Sejong and the ministers closely examined the target board. While examining the target board, Jo Mal-saeng shared his thoughts with Sejong.

“Any Jurchen or Japanese pirates who come within 30 paces will likely see hell.”

“Do you think so?”

“Yes!”

At Jo Mal-saeng’s affirmation, Sejong looked at Choi Hae-san and Lee Chun. Their faces, hardened from their martial lives, were filled with confidence. Seeing their faces, Sejong nodded.

“Looking at your expressions, I understand. Now, about the armor…”

“Your Majesty, I apologize. There are still other firearms left to introduce.”

“Still?”

Sejong looked slightly bored. Just from the cannons they had seen, the hard work that the crown prince and his followers had put in was evident.

If they could properly supply the gunpowder and cannons, securing the safety of Joseon would be as easy as turning the palm of the hand.

‘No, with a little more effort, we could recover the former territories of the Three Han, just as Yangnyeong-hyungnim¹ once said!’

While suppressing the greed that was growing within him, Choi Hae-san was reigniting the flame.

Just as Sejong was about to leave his seat, he sat back down at Choi Hae-san’s words.

“General! Proceed!”

“Your Majesty, the weapon we will introduce next is a fire bomb. We must move to a different location.”

“…Lead the way.”

“Yes, Your Majesty.”

Following Choi Hae-san’s guidance, Sejong moved.

“The distance is quite far?”

As Sejong started to pant a bit, Hyang explained the reason, “Given the nature of the location…”

“Should I have ridden a horse?”

“Your Majesty. It is said that a man’s two legs are like the pillars of a house. A house is sturdy only when its pillars are sturdy…”

When Hyang tried to give a lengthy speech about health, Sejong hurriedly cut him off, “…Just walk, walk.”

“The legs need to be strong to prevent impotence”

“I said I’m walking! My, my, what a talkative child! Always on about impotence… How did I give birth to such a child…”

While grumbling continuously, Sejong moved his steps even bigger.

The place where Choi Hae-san and Lee Chun led Sejong was even larger than the previous demonstration ground. Not only was it larger, but there were also taller and thicker earthen walls erected.

In front of the platform where Sejong and his ministers sat, walls of dirt piled in bags were placed even higher and thicker than before. On the opposite side was the beginning of Mount Mokmyeok², with a bare patch of ground at least 50 meters in length and width visible.

“Did they cut down the trees?”

“Yes, because a fire could occur.”

“What a shame…”

As Sejong and his ministers took their seats on the platform, the waiting artisans and soldiers brought a large table and quickly placed various tools on it.

Beside the table, Choi Hae-san began to introduce the new weapon.

“The fire bomb that I will show you now is a fire bomb that is launched from a trigger.”

Choi Hae-san pointed at a round fire bomb made of iron with a baton.

“We named this fire bomb Flying Strike Sky-shaking Thunder³.”

“Flying Strike Sky-shaking Thunder… Is it a kind of Sky-shaking Thunder?”

“What is Sky-shaking Thunder?”

“I have only read about it in records, but it’s said to be similar to a canister gun. It was used by the Song and Jin dynasties, according to the records.”

“Is ‘Flying Strike’ added because it uses a trigger?”

The ministers shared their thoughts, trying to remember their knowledge as Choi Hae-san explained. Watching the ministers’ reactions, Hyang showed a smug smile.

‘The hallmark of King Munjong is the Singijeon (fire arrow rocket launcher) and Hwacha (multiple rocket launcher), but we can’t overlook the cliché! The ultimate cliché! On the sea, there are Turtle Ships, and on the land, there is the Flying Strike Sky-shaking Thunder!’

1. Grand Prince Yangnyeong, eldest prince of King Taejong, a.k.a. Sejong’s older brother.[↩]
2. An old name for current Namsan[↩]
3. The long-ass name, LOL[↩]