Chapter 56: New Weapons (4)
After praising the excellence of the musketeers, Sejong moved to the main topic.
"Are the chongtongs they carry on their shoulders the newly made ones?"
At Sejong's question, Hyang answered immediately.
"Yes, Your Majesty. That is correct. I have named it the Gap-style Long Chongtong."
At Hyang's answer, Sejong stroked his beard and shared his thoughts.
"Long Chongtong... a fitting name. But..."
Sejong's gaze fixed on the gleaming barrel of the Long Chongtong. Looking at the silver-gleaming barrel, Sejong turned his head toward Hyang.
"It's not made of copper, is it?"
"That is correct. It was made from si-u-soe (wrought iron)."
"From si-u-soe?"
Hwang Heui, who was listening to the conversation between Sejong and Hyang, immediately interjected.
"Your Highness, copper is expensive, but si-u-soe also has a price..."
Sejong raised his hand to cut off Hwang Heui's words.
"Enough. The Crown Prince must have had some thought in mind to use si-u-soe. We can discuss that matter later; it won't be too late."
"I obey your command."
Having stopped Hwang Heui's words, Sejong gave an order to Choi Hae-san.
"I wish to see its power."
"Yes, Your Majesty."
Receiving the order, Choi Hae-san signaled the craftsmen standing beside him. Seeing Choi Hae-san's signal, the craftsmen soon brought out a board about the size of a human torso. The board, covered with red cloth, had dou-ding (iron studs) lined up on it. Choi Hae-san pointed at the board with his baton and began his explanation.
"This is a dou-ding board to be used as a target. Compared to actual dou-ding armor, the thickness of the iron plates has been increased by 1 ri to 4 ri (approximately 1.3mm)."
"Is that so?"
"Set up the target."
"Yes, General."
The craftsmen carried the target to the opposite side of the demonstration field. Seeing the target being set up quite far from where the musketeers were positioned, Sejong called out to General Choi Hae-san.
"General, what is the distance to that point?"
"Approximately 250 paces (about 300m), Your Majesty."
"Oh!"
Sejong exclaimed and his eyes began to shine. Meanwhile, the craftsmen who had finished setting up the target made hand signals and quickly ran to the side, throwing themselves into a ditch dug beneath the earthen wall.
Seeing the craftsmen's hand signals, the commander shouted to the musketeers.
"Stand the gun!"
At the commander's order, the musketeers stood the Long Chongtongs they had been carrying on their shoulders on the ground.
"Clean the barrel!"
"Insert gunpowder!"
"Insert paper!"
"Insert the bullet!"
"Insert the lead ball!"
Having completed all the processes according to the commander's commands, the musketeers returned to the standing gun position, and the commander gave the order.
"Present arms! Copper flash pan!"
The musketeers raised the Long Chongtongs, pulled the hammer halfway, then inserted the copper flash pan containing the priming powder onto the lug.
"Cock the hammer! Aim!"
The musketeers pulled the half-cocked hammer fully back, extended their left foot forward, positioned their bodies diagonally, pressed the stock against their shoulders, and aimed at the target standing far away.
"Fire!"
Bang-bang-bang!
In an instant, billowing smoke and sparks burst forth and disappeared into the air.
"Secure!"
Having finished firing, the musketeers returned to the standing gun position, and the craftsmen who had hidden in the ditch retrieved the target and returned.
"Amazing!"
"Such tremendous power!"
Sejong and the ministers, examining the retrieved target board, could not hide their astonishment.
There were 9 holes punched through the target board.
The faces of Hyang and Choi Hae-san, watching Sejong and the ministers examining the target board with surprised expressions, were filled with pride.
"Truly amazing. As far as I know, while chongtongs have strong power, their range falls far short compared to bows. However, this Long Chongtong has a range similar to bows, and its power is incomparable. Truly, it is the strongest weapon."
"The craftsmen have worked hard."
At Sejong's praise, Hyang answered humbly. Watching from the side, Choi Hae-san nodded vigorously. In the eyes of Choi Hae-san, nodding like that, small tears were welling up.
At Choi Hae-san's intense reaction, Sejong turned to look at Hyang. Seeing Hyang's face wearing a faint smile, Sejong sighed.
"Just how much did you make the craftsmen suffer... General Choi. Tell me the process of completing this chongtong."
"Yes, Your Majesty. Well..."
* * *
The beginning of the process of making the Long Chongtong started with making dedicated tools for creating the iron body of the Long Chongtong.
"To make chongtongs using the discard method, we must also use a dedicated anvil."
Following Hyang's order, the craftsmen made a dedicated anvil using bong-soe (high-carbon steel). While a typical anvil had a flat top, the dedicated anvil had long grooves carved in the shape of half-cylinders, gradually narrowing from a large half-cylinder to one slightly larger than the target chongtong's thickness.
After the anvil was completed, what Hyang requested was an iron core made of bong-soe, slightly thicker than the chongtong's bore.
Once the dedicated tools were made, Hyang guided the next process.
Following Hyang's guidance, the blacksmiths of the Military Arsenal, including Master Blacksmith Go, began rolling appropriately sized wrought iron plates.
After the iron plates were moderately rolled, they placed the iron core in the center and began hammering and rolling the iron plates on the dedicated anvil. As the iron plate rolled and both ends met, the craftsmen sprinkled a mixture of iron powder and charcoal powder on the joined part, then put it in the kiln. As the iron powder mixed with charcoal powder melted in the intense heat of the kiln, the seams of the rounded iron plate were filled.
Once the gaps were completely filled, the blacksmiths filed them smooth and simultaneously checked whether they were properly filled. If filled without issues, they hammered the round barrel to make it appropriately angular.
This was to make it easier to secure the chongtong during the subsequent processing steps.
Finally, after heating in the kiln and cooling in ash, the chongtong was smoothed internally using a drilling machine Hyang had designed.
Once the inside was smoothly bored and it was confirmed that both the inside and outside of the chongtong were straight without warping, the craftsmen filed the barrel to give it an octagonal cross-section. Afterward, they cut female threads in the rear part and inserted a plug with male threads - this part had a component for attaching the copper flash pan.
The work did not end there. The wooden stock made by the carpenter was combined with the trigger, hammer, and chongtong; the trigger guard, front sight, and rear sight made by the metal craftsman were attached; and at the muzzle end, a sturdy iron ring with protruding lugs on both sides was fitted. The hardship began from then on. The barrel on the blueprint Hyang created did not have rifling. This was Hyang's intention.
"In the future, the things we need to make and test will continue to increase. I can't step forward and do everything myself, can I?"
Once five prototypes were completed, Hyang began full-scale performance testing with Choi Hae-san and Yi Cheon.
"First, let's find out how much gunpowder it can withstand."
"Yes, Your Highness."
"The existing I-chongtong used one nyang, so shall we start with half a nyang?"
"That seems appropriate."
Choi Hae-san, Yi Cheon, and the craftsmen began the test by loading half a nyang of Gap-style gunpowder and bullets.
For safety, they secured the chongtong in a fixture, connected a string to the trigger, and people hid behind a protective wall.
"Fire! Fire! Fire!"
Bang!
The test that filled Area 51 with explosive sounds ended with the weapon withstanding up to one and a half nyang of Gap-style gunpowder.
"Considering the purpose of this chongtong, I don't think we need to test 2 nyang."
"You are correct."
"Then let's try with Eul-style gunpowder."
In the subsequent test, the Long Chongtong also withstood up to one and a half nyang of Eul-style gunpowder. After confirming the results, Hyang changed the test item.
"Then let's confirm what the optimal amount of gunpowder is. They said the distance at which the I-chongtong killed Jurchens wearing dou-ding armor was 40 paces (about 50m), so let's use that as the standard."
"Yes, Your Highness."
This time, they would reduce the amount of gunpowder. The result of the test was 2 don (about 7.5g) of Eul-style gunpowder. The bullet fired from the Long Chongtong cleanly penetrated the 4 ri thick iron plate used as the target.
After confirming the results, Hyang turned to Choi Hae-san and Yi Cheon.
"Looking at the power, it seems possible to kill at even greater distances, right? The further the better, wouldn't you agree?"
"Naturally so."
"Then shall we try 50 paces?"
"Yes, Your Highness."
Choi Hae-san answered excitedly. In the test conducted this way, the Long Chongtong loaded with 2 don of Eul-style gunpowder penetrated the target up to 70 paces (about 85m). At greater distances, the bullets reached the target, but even after firing more than 20 rounds, not a single one hit.
'70 paces, that's better than expected. Now it's time to drop the hint about rifling?'
Although the results were better than he expected, Hyang had no intention of stopping.
And from that point on, things stopped being enjoyable for Choi Hae-san, Yi Cheon, and the craftsmen.
"General, looking at the loading process of the chongtong, it seems too much time is consumed by cleaning the barrel and tamping. Let's try without cleaning and tamping."
"But without that process, there's a concern that the bullet might slip out..."
"Instead, couldn't we make the bullet fit the chongtong precisely?"
At Hyang's opinion, Choi Hae-san thought for a moment and then nodded.
"It seems worth testing."
Hyang planned to force them through trial and error based on the content of a video he had seen on the internet. In the experiment conducted this way, the Long Chongtong fired 5 rounds and then developed a problem.
"Gunpowder residue is stuck, making it difficult to prepare for the next shot."
"I see."
"So we do need to clean the barrel after all..."
However, Hyang shook his head.
"General, think about it. When cavalrymen riding horses that run faster than people charge at full speed, would there be time to clean the barrel?"
"That is true, but..."
Choi Hae-san, Yi Cheon, and the craftsmen put their heads together to find a solution. However, people could not easily come up with the idea of rifling.
'Do I need to step in again?'
While Hyang was pondering whether to intervene, on one rainy day, a craftsman who had been blankly staring out the window suddenly jumped up from his seat.
"Ah!"
"What is it!"
"How about carving grooves?"
"Grooves?"
The craftsman pointed to the ground with his finger and explained.
"Look at that ditch. Doesn't the standing water flow out through that ditch? Gunpowder flames also have a flow, so wouldn't it be the same? If we carve long grooves inside the chongtong, wouldn't the residue also flow out along with the flame's flow through the grooves?"
At the craftsman's words, Choi Hae-san and Yi Cheon looked at Hyang. Hyang nodded.
"It seems worth testing."
Following Hyang's decision, 7 additional Long Chongtongs were produced.
"Let's make 2 Long Chongtongs each with 3, 6, 9, 12, and 15 grooves, and compare them with the Long Chongtong without grooves."
"Yes."
Though they received the order, the craftsmen had a new concern.
'How do we carve the grooves?' After worrying for several nights, a dedicated tool was created, and the craftsmen carved 3 to 15 grooves in the Long Chongtongs.
In the subsequent test, Choi Hae-san, Yi Cheon, and the craftsmen encountered a new problem. The more grooves there were, the more the power decreased.
"That would be expected. The more grooves there are, the more force will leak through those grooves."
When Yi Cheon pointed out the cause, Choi Hae-san muttered with a troubled expression.
"So cleaning the barrel is the only answer after all?"
"What are the exact results?"
At Hyang's question, Yi Cheon answered while flipping through the book with recorded results.
"Up to 6 grooves, the power reduction is minimal but much residue accumulates. From 9 grooves, less residue accumulates, but the power begins to drop rapidly."
At Yi Cheon's answer, everyone grabbed their heads.
"Should we go with 9 grooves..."
"The problem is that the power drops visibly from that point..."
"Then is 6 grooves the only answer? But that has the residue problem..."
Seeing them agonizing over problems that couldn't be solved simultaneously, Hyang was about to open his mouth when Jang Yeong-sil spoke.
"Then how about twisting the grooves?"
"Twisting the grooves?"
At Jang Yeong-sil's statement, everyone's attention focused on Jang Yeong-sil.
Watching this from behind, Hyang clenched his fist under the desk.
'Uncle, nice!'
Quickly composing his expression, Hyang ordered Jang Yeong-sil.
"Chief Jang, please explain properly."
"Yes, Your Highness. Well... um... if we twist the grooves like the screws we use, wouldn't the length increase? That way, even if there are 6 grooves, the length would be sufficient for the residue to escape, and also, since it twists, the explosive force of the gunpowder wouldn't escape straight out, would it?"
At Jang Yeong-sil's explanation, the conference room fell silent. While everyone was pondering for a while what Jang Yeong-sil's words meant, Choi Hae-san and Yi Cheon shouted simultaneously.
"That's it!"
"That's it! Crown Prince, twisting seems to be the answer!"
At the words of Choi Hae-san and Yi Cheon, Hyang concluded.
"Then let's do it."
That night, as he went to bed, Hyang grumbled with an exhausted expression.
"Ah... the road to rifled guns is truly long and rugged... To explain the concept of surface area as length... And that comprehension to understand it instantly... Are all the people living in this era monsters?"
The decision was made to twist the grooves carved inside the chongtong, but problems arose again there.
"How many turns should we make?"
When people were wandering again in front of this problem, Hyang had to step forward once more.
"Make prototypes from half a turn to two turns, in half-turn increments!"
"I obey your command!"
And so the craftsmen had to stay up all night again to make new Long Chongtongs.