Chapter 57: New Weapons (5)
It was decided to carve large rifling grooves inside the long gun barrel, but the craftsmen fell into another dilemma.
"Which direction should it rotate?"
As they worried about the rotation direction of the rifling, Hyang made a conclusion.
"Looking from the muzzle, why not make one in the direction of clock hands, and one in the opposite direction?"
At those words, Choi Hae-san opened his writing board and began calculating.
"From half a rotation to two full rotations, that's 4 types. Add 2 rotation directions, and we need to check for variance, so at minimum 5 barrels each... that makes 40 barrels. This will take some time."
"We must put in the effort."
At Hyang's words, the craftsmen present let out small sighs. However, no one complained. The work was difficult, but firing the guns unexpectedly cleared their minds, and checking the results had its own fun.
Of course, Choi Hae-san and Lee Cheon, caught in the middle, had more headaches than fun.
In the subsequent tests, all 40 guns showed results beyond expectations. All 40 could fire more than 5 rounds without problems, and little degradation in power was observed.
However, in the process of analyzing the test results, an unexpected result appeared - the accuracy was remarkably higher than expected. Excited by the unforeseen result, Choi Hae-san submitted a report and made a suggestion.
"Until now, at 70 paces distance, firing 20 rounds and hitting 5 was considered lucky. But in this test, all 40 guns hit the target at 70 paces distance. Research on this matter is necessary!"
"I see. Let's do it! Prepare."
"Yes, Your Highness!"
Watching Choi Hae-san's back as he left excitedly, Hyang clenched his fist.
'Yes! We got it!'
To find the cause of the unexpected result and how to utilize it, Choi Hae-san, Lee Cheon, and the craftsmen fired hundreds of rounds.
Through this process, the military officers and craftsmen learned several facts.
- The rotation count of the grooves carved inside the barrel performed best at one and a half rotations.
- When firmly secured to the mounting fixture and fired, the bullet hit targets up to 500 paces (approximately 600m) away. However, this literally meant hitting the target board, not a bullseye.
- However, this did not mean the firing range from the barrel increased. Regardless of the presence of rifling, 2 don (approximately 7.5g) of gunpowder could launch a 5 don (approximately 17g) bullet up to 800 paces (approximately 960m).
- When hitting at 500 paces distance, the bullet did not penetrate the iron plates used as targets. However, judging from the dented state of the iron plates, it is estimated that it could inflict significant injury on enemies.
- The direction of rotating the grooves should be unified with the direction in which the barrel body and cap tighten. If done in reverse, the more shooting is done, the more the barrel body and cap will loosen.
"Your Highness, how about experimenting with increased gunpowder quantity?"
Choi Hae-san and Lee Cheon showed enthusiasm, but Hyang shook his head.
"There is a high possibility of repeating the problems of existing guns."
"Ah..."
"Rather than that, let's systematize the results we've secured."
"Yes, Your Highness."
Hyang, Choi Hae-san, and Lee Cheon classified the surveyed results as follows:
- Maximum Range: The farthest distance a bullet travels when fired with the prescribed gunpowder and bullet. The bullet's power is almost nonexistent.
- Maximum Effective Range: The distance where at least 30% accuracy can be expected when aiming and firing. However, it must maintain enough power to inflict a certain level of injury on the target.
- Effective Range: The maximum distance at which trained gunners can hit a target when aiming and firing.
According to the classification established by Hyang, Choi Hae-san, and Lee Cheon, the performance of the gun with rotating grooves was: maximum range 800 paces, maximum effective range 350 paces, effective range 250 paces.
While Hyang, Choi Hae-san, and Lee Cheon expressed considerable satisfaction as they classified the results, the researchers and craftsmen at the institute were pondering to solve the homework Hyang had given them.
"'Analyze why the performance of the long gun suddenly improved.'..."
"Looking at the test results conducted so far, the only reason for such a dramatic improvement in performance is the rotating grooves. But why did such a result occur..."
"Exactly. That's the problem..."
The most likely suspect was the 'rotating grooves,' but the officials and craftsmen couldn't easily figure out what those grooves had done.
While the officials and craftsmen were worrying, an arrow maker from the Military Ordnance Directorate offered an opinion.
"Isn't it that those grooves make the bullet rotate?"
"Make the bullet rotate? Tell me more."
The arrow maker explained in more detail, even using hand gestures.
"When we attach feathers to arrows, we attach them slightly at an angle. Then the arrow that leaves the bowstring flies while spinning round and round like this. And what happens then? The arrow flies straight. It's also less affected by crosswinds."
"Is that so?"
Thinking it plausible, the officials and craftsmen conducted tests with various bullet sizes. As a result, it was confirmed that the bullet, meshing with the protruding parts of the rotating grooves, rotated and brought about improved accuracy.
The knowledge discovered this way and the data obtained during the test process were all documented, and this was strictly stored in a safe located in the deepest part of the archive.
"This is a top-class secret connected to our Joseon's national defense, so everyone must pay attention to keeping it strictly confidential."
At Hyang's warning, the officials and craftsmen answered in unison.
"We will bear it in mind etched in our bones!"
* * *
Such confidentiality was maintained even while the inspection was taking place. While explaining to Sejong the process of making the gun, Choi Hae-san did not reveal the part about these rotating grooves until the end.
It was only after the inspection ended that Sejong learned about this matter. Choi Hae-san, who met with Sejong alone, submitted a written report, and after reading the document, Sejong nodded.
"I understand why the Crown Prince and you kept this secret until the end. Then I must follow suit. Attendant, bring the brazier."
Sejong threw the report he had finished reading into the brazier and burned it.
Meanwhile, while Choi Hae-san was reporting to Sejong in writing, Hyang muttered while looking at related records.
"Once the performance of the long gun becomes known, it will definitely leak out. Whether captured in battle, stolen, or sold for back-alley money. And they'll excitedly try to replicate it. But by the time they understand the principle and attempt improvements, our Joseon will be one step ahead. That's why we're doing all this."
* * *
"I'll say it again, truly excellent weapons have been created."
"I plan to unify all guns used by gunners to this Gap-sik long gun."
At Choi Hae-san's words, when Hwang Hee tried to say something, Sejong raised his hand to stop Hwang Hee's words.
"Hmm... If we deploy them sequentially starting from the northern regions, it should be fine. Good! Let's review that plan."
"We are grateful for your grace!"
"We are grateful for your grace!"
When Sejong reached a positive conclusion regarding the production and deployment of Gap-sik long guns, Hyang, Choi Hae-san, Lee Cheon, and other officials all bowed simultaneously and shouted, "We are grateful for your grace!"
"Good. Is the gun decided with this?"
"No. There is one more type of gun. The cavalry gun."
"Oh?"
When Sejong showed interest, Choi Hae-san made a hand signal. At Choi Hae-san's signal, a military officer wearing blue armor entered.
"The color of the armor..."
"This is new armor developed together. I will explain later."
"Is that so? Then proceed."
At Sejong's command, Choi Hae-san continued.
"What I will show Your Majesty this time is the Gap-sik cavalry small gun."
When Choi Hae-san finished speaking, the military officer opened the lid of a long leather pouch hanging at his right waist, took out a silver-colored gun, folded his arm, and held it with the muzzle pointing upward.
"I want to see it in detail."
"Yes, Your Majesty."
At Sejong's command, the military officer placed the gun on both hands and respectfully presented it. Sejong, who received the gun from the military officer, examined it this way and that, and his gaze stopped at the round metal cylinder attached to the middle of the gun.
"Six holes? By any chance, can this gun fire six shots?"
"That is correct."
"Huh!"
Greatly surprised, Sejong looked back at Hyang.
Looking at Sejong's surprised eyes, Hyang answered with a smile.
"It is one of the masterpieces of District 51."
'Of course, the design was based on something that already existed.'
What was in the military officer's hand was a Colt 1860 Army modified to a caliber suited to the Joseon military situation. This was something Hyang had been preparing as a successor to the Kentucky Rifle when he was living in the 21st century.
At Hyang's answer, Sejong returned the gun to the military officer and said,
"I want to see how it's fired."
"Yes."
In the subsequent demonstration, the military officer hit all 6 shots on a target board set up 30 paces (approximately 36m) away. The target board that the craftsmen retrieved and brought had 6 holes cleanly pierced through it. The craftsmen turned the target board around. Behind the red cloth with target circles, iron plates were firmly embedded.
Sejong and the ministers examined the target board thoroughly. Jo Mal-saeng, who was examining the target board, shared his impression with Sejong.
"The Jurchens and Japanese pirates who come within 30 paces at least will see hell."
"You think so?"
"Yes!"
At Jo Mal-saeng's assertion, Sejong looked at Choi Hae-san and Lee Cheon. Their faces, roughened by long experience as military men, were full of confidence. Sejong, who confirmed their faces, nodded.
"Looking at your expressions, I understand well. Then, about the armor..."
"Forgive me, Your Majesty. There are still firearms left to introduce."
"Still more?"
Sejong's face showed slight exhaustion. Even with just the guns he had seen now, the effort put in by the Crown Prince and those under him was visible.
If gunpowder and guns could be properly supplied, securing Joseon's safety would be as easy as turning over one's hand.
'No. With just a little more effort, we might be able to recover the former lands of the Three Han as Crown Prince Yangnyeong said!'
While he was barely suppressing his growing greed, Choi Hae-san was lighting the fire again.
Sejong, who was about to leave, sat back down at Choi Hae-san's words.
"General! Proceed!"
"We are grateful, but the weapon to be introduced this time is an explosive shell, so we must move to another location."
"... Guide us."
"Yes, Your Majesty."
Sejong moved his steps following Choi Hae-san's guidance.
"The distance is quite far?"
At Sejong's slightly rough breathing, Hyang explained the reason.
"Given the nature of the location..."
"Should have ridden a horse?"
"Father. They say a man's two legs are like the pillars of a house. For the house to be strong, the pillars must be strong..."
When Hyang tried to launch into a lecture about health, Sejong hurriedly cut him off.
"... I'll walk, I'll walk."
"For the legs to be strong, you need to prevent edema..."
"I said I'll walk! Geez, this kid talks so much! Every time he does something, it's edema this, edema that... How did I end up with such a son..."
While continuously grumbling with his mouth, Sejong walked with even greater strides, putting more strength into his steps.
* * *
The location where Choi Hae-san and Lee Cheon guided Sejong was an even larger place than the earlier demonstration site. Not only was it larger in scale, but higher and thicker earthen walls were erected.
In front of the platform where Sejong and the ministers were seated, a wall made of sandbags was positioned even higher and thicker than before. The opposite side was where the foothills of Mokmyeok Mountain began, with bare ground measuring at least 50 jang in width and length exposed.
"Did you cut down the trees?"
"Yes, because there was a possibility of fire."
"Well then..."
When Sejong and the ministers took their seats at the prepared area on the platform, the waiting craftsmen and soldiers brought a large table and then placed various implements on it.
Choi Hae-san, who was positioned beside the table, began introducing the new weapon.
"The explosive shell I will now show you is one fired from a wan-gu (mortar)."
Choi Hae-san pointed to a round explosive shell made of iron with his baton.
"We have named this explosive shell the Bi-gyeok-jin-cheon-ryeo (Flying Strike Heaven-Shaking Thunder)."
"Bi-gyeok-jin-cheon-ryeo... Is it a type of Jin-cheon-ryeo?"
"What is Jin-cheon-ryeo?"
"I've only seen it in records, but it's said to be similar to the Jil-lyeo-po-tong. Records say Song and Jin used it."
"Is 'Bi-gyeok' attached because it uses a wan-gu?"
At Choi Hae-san's explanation, the ministers searched their memories and exchanged opinions. Watching their reactions, Hyang smiled faintly.
'When you think of King Munjong, people think of Singijeon and hwacha, but you can't miss the clichés! The cliché of all clichés! At sea, the turtle ship, on land, the Bi-gyeok-jin-cheon-ryeo!'