After the six-hour trading period, it was three o'clock in the afternoon when Su Mo stepped out of the door of light. The golden light behind him shattered twenty or thirty seconds later.

The light gradually turned into a spot of light, fell to the ground, and melted into the drifting snow.

Except for the shelter and the mountain of materials piled up at this time, the peaceful scene in the basin had once again been restored.

3200 units of iron were divided into two layers and densely covered the surroundings of the Underground Shelter, covering an area that spanned three or four acres.

It was the same for the blocks of copper, which lay neatly on the ground on the left side of the Underground Shelter.

Given the current space within ​​the Underground Shelter, these materials could not be stored even if the shelter doubled in size several times. They could only be temporarily piled outside.

"It's great, in the basin, no one else can detect that I have this many materials, so I don't need to fear them being stolen even if I store them outside."

Su Mo casually walked on the blocks of iron. With Oreo standing guard, he was not afraid of people coming to steal the resources near the shelter.

Even if there were any attempts, these people's small and poor storage space alone could not take many at a time, so he was not worried at all.

After using the storage space to move all the steel blocks into the garage, Su Mo picked up five units of copper blocks and nervously went to the second floor to turn on the generator.

After days of adventures, traveling around and even risking his life, he had finally profited from the exchange of supplies.

His effort had transformed into strength on the final day!

Looking at the small thermal weapon laser manufacturing machine that had already begun its self-inspection process, Su Mo was excited.

Operating a laser manufacturing machine was not difficult. After adding the magical modular technology, the manufacturing process had been greatly simplified.

He only needed to select the weapon option, put in the required materials, and pass the machine's inspection process, then all he needed to do was wait for the finished product to be produced by the foolproof operations of the machine.

"Modular technology is indeed a great thing. It's a pity that I did not acquire a modular machine component this time around."

"But even if there was one, these people may not sell them unless they were on the verge of dying."

Su Mo shook his head and put away his greedy thoughts. Seeing that the green light had lit up after the self-inspection process, he lightly tapped on the M-1 rifle option, and the list of required materials popped out.

Three units of steel, two units of iron, one unit of copper, one unit of wood, two units of water, and...

Ten degrees of electricity!

The laser manufacturing machine had its own battery module that needed to be charged with a higher amount of power than the manufacturing value before it could start operating.

This was a requirement to prevent the possibility of a sudden power failure causing a manufacturing failure to occur, or causing damage to the machine itself.

Seeing that the fast charging process had started at the bottom right, Su Mo was not impatient. He quietly sat in front of the machine and waited.

The creation of firearms involved some seemingly simple, but very complex, specifications. For example, rifling is a very simple but very important part of the process.

Rifling refers to the cross-sectional grooves on the internal surface of a gun's barrel.

Rifling can be said to be the soul of the barrel. The function of the rifling is to give the bullet the ability to rotate so that it can maintain its established direction after being fired from the barrel.

Although there were records of the usage of rifling dating back to the 15th century, it was not popularized until the 19th century due to the difficulty of the manufacturing process.

Without the relevant knowledge and resources, Su Mo could only hope that the laser manufacturing machine would be capable enough not to make any mistakes!

After half an hour had passed, the charging process was completed. Looking at the manufacturing button that popped up on the side of the machine, Su Mo profoundly and gently put all the materials into the storage module of the machine, which measured only one cubic meter, and pressed the manufacturing button with both his hands to start the process of building firearms for the first time!

Squeak! Squeak!

The harsh sound was accompanied by a slight jittery burst from the machine as the button was pressed.

The terrifying high-pitched cutting sound not only frightened Su Mo, but even Big Spark and Little Spark on the second floor cooed in fright.

The laser tool above began to slowly rotate under the guidance of the machine.

Before Su Mo could take a good look at how the machine made weapons, an iron cover suddenly rose from both sides of the machine.

Driven by the electric motor, the cover began to slowly form a sphere, leaving only a few holes for heat dissipation, and completely covering the entire machine.

Then, a dazzling burst of light erupted from the heat dissipation holes of the cover, lighting up the research center with an unusual brightness.

The high temperature caused by laser cutting began to seep out of the heat dissipation holes.

Gradually, as the temperature got higher and higher, Su Mo simply summoned the lion clan's wind ability to start dissipating the heat of the big iron ball.

This cycle repeated itself over five minutes, before the light rays started to diminish.

Puff!

As the water vapor erupted, the cover began to slowly descend, revealing the contents inside.

At this time, in the place where the finished product lay, there was already a newly-produced gun, which seemingly shone brightly and looked very aggressive.

Scrutinizing the ends of the gun starting from the tip of the gun, Su Mo carefully looked over the body of the gun. Faced with this momentous harvest, Su Mo remained calm.

The green indicator light lit up again, indicating that Su Mo could pick up the gun, as the temperature of the M-1 rifle had dropped and reached a stable temperature.

Picking up the gun, Su Mo felt its weight.

"It's not too heavy. The weight of an empty gun is about five catties. After refilling the bullets, it should be between six and six and a half catties."

Removing the magazine, Su Mo looked at its capacity.

The bullet caliber size of the magazine was 5.56 x 45mm. It used a STANAG magazine similar to that on Earth, with a standard capacity of 40 rounds of shooting.

"Without considering the different name and pattern design of this gun, it was essentially a pirated M4A1 rifle."

Stroking the intricate patterns on the body of the gun, Su Mo was not sure how powerful it was, so he could only attempt to start up the machine again to create ammunition.

The M-1 rifle used M193 rifle bullets, which was a conventional 45mm caliber bullet. This small-caliber rifle was able to produce a lethal force that belied its smaller size.

The M193 bullet does not have a steel core. Instead, the bullet is filled with soft lead, and the copper coating on the outside of the bullet is very thin, resulting in the entire bullet becoming very soft.

When impacting the target, the warhead will quickly deform and shatter into smaller bullet fragments, causing additional wounds and penetration around in the initial wound, which in turn would cause serious bleeding.

However, the technology tree of firearms was not as simple as just making firearms.

The biggest problem facing all human beings in the wasteland was the preparation of ammunition.

Even if the current Underground Shelter was full of materials, to create suitable bullets, a new technology tree was needed...

Smokeless gunpowder!

The rate at which gunpowder burned was slow, and its low pressure also resulted in a reduction in the speed at which a bullet was ejected from the chamber.

To achieve sufficient range and effectiveness, simple physics meant that the bullet required a larger mass and caliber.

Therefore, rifle bullets of more than ten millimeters or even 20 millimeters abounded during the era of gunpowder.

To achieve better results, in the late gunpowder era, compressed gunpowder was loaded to increase the chamber pressure, which could also provide a speed close to that of smokeless gunpowder.

Smokeless gunpowder would burn faster, and had higher pressure and temperature, which in turn resulted in faster speed. It also reduced the caliber and quality of the ammunition required, reduced the logistical burden, and ushered in countless design changes, while also making bullets fly faster and with straighter trajectories.

A straighter trajectory would reduce the effect and error margin when shooting from a distance.

For example, when firing at an exposed head in trench warfare combat, the usual distance required for accurate shots was about 300m. A small difference of a few meters from this ideal distance would likely result in a high or low impact shot.

The straighter trajectory would also reduce the trajectory height error caused by the distance, making it easier to hit the target.

"The preparation method of smokeless gunpowder in the TV series Hanyang Zao was a bit exaggerated, but there are other places to refer to..."

Placing the M-1 rifle on the workbench, Su Mo began to think carefully about how to manufacture smokeless gunpowder in batches.

If the development of the ammunition technology tree was not promoted, no matter how awesome the guns he would use in the future might be, it would be useless if he did not have the bullets for them.

"The production process of nitrocellulose, or guncotton, is not troublesome, but finding a suitable cotton is a problem. After that, I'd only need to soak the guncotton with ethanol and ether, and dry it to get smokeless gunpowder."

"Ethanol and ether are not difficult to prepare. Ethylene can be extracted from petroleum, and ethylene can be used as a raw material for ethanol. Ethylene can be hydrolyzed to obtain ethanol, and ethanol can be catalyzed by the catalytic reaction to obtain ether."

Taking out a piece of paper, Su Mo recalled as much chemistry knowledge as possible, including from TV series, and put them together. He completed the specious idea of ​​making smokeless gunpowder.

A light flashed and, after a systematic identification, it was confirmed that there was no problem with this design blueprint at all, and that the concept behind it was correct.

"So, the last hurdle is the cotton? The quality of cotton is very important in making the right guncotton!"

In the Hanyang Zao TV series, Xu Jianyin once presided over the research and development of sulfuric acid in Tianjin Manufacturing Bureau, which solved the problem of relying on the import of sulfuric acid at that time.

It was Zhang Zhidong who had taken a fancy to his outstanding talents, so he poached him to Hanyang Steel and Pharmaceutical Factory to be responsible for the production of ammunition.

One of the main raw materials for making gunpowder was cotton. In his research, Xu Jianyin found that there was a big difference between domestic cotton and foreign cotton.

Therefore, the temperature, humidity, time, pressure, liquid concentration, etc, would change during the domestic trial production. Perhaps this was the main reason for the failure of the Jiangnan Manufacturing Bureau.

To quickly find a suitable production method for China, Xu Jianyin "hand-grinded" the mortar and studied it himself.

It took only half a year before they finally produced a sample of smokeless gunpowder.

After testing, the effect of the sample was completely comparable to the imported smokeless gunpowder.

This also showed that, as long as you had the right cotton, you could make quality smokeless gunpowder in a very short time.

"System, how many survival points are needed to create a pound of cotton used to make guncotton?"

Without hurrying to buy it on the market, Su Mo opened the system panel and clicked on the creation interface. He first recorded down the requirements of the system.

The price was not low, but not high either.

65 survival points could be exchanged for a catty of cotton used to make guncotton, 300 points could be exchanged for a catty of manufactured gunpowder, and 520 points could be exchanged for a catty of developed smokeless gunpowder.

A bullet needed to be filled with about 2g of gunpowder. A catty of gunpowder could fill 260 bullets. After conversion, this exchange rate for gunpowder meant that the cost of a bullet was close to 2 survival points, which would be a terrible loss!

"No, since I will definitely use bullets in the future, I must have a suitable assembly line for ammunition. I will simply buy the cotton and practice the production process myself!"