Jiajing would actually give the Heiyanshan Coal Mine to Lu Ling'er, this Yang Cong really didn't expect it, he just wanted to give Chen Hong some eye medicine, so as not to take the opportunity to install his own people when Jiajing sent the mine supervisor next time, but he didn't expect to pick up such a big bargain for nothing.

Although coal is not worth much at this time, it is just that there are few people who use it, in fact, the value of coal is not much different from that of later generations, a coal mine is worth hundreds of thousands of taels of silver, if the reserves are large, it is worth millions of taels It is possible, and giving it to Lu Linger is actually equivalent to giving it to him.

It's such a big bargain, don't do it in vain, even if he arranges for the Yang family shopkeeper to take over the Heiyanshan Coal Mine, as for the next mining, it is naturally a vigorous digging, anyway, the coal dug up will definitely be used in the future.

Jiajing's move also proves that he attaches great importance to the manufacture of weapons and equipment in Xuanfu Town, and there must be no problem in mining copper ore.

Yang Cong then played on him, please open the Chicheng Copper Mine, and in the play, he also explained the reason for inviting the Chicheng Copper Mine.

However, he didn't explain in too much detail, he didn't say anything about the development of rear-loading guns, he just said that iron guns are too difficult to process, if you want to manufacture guns equipped with 60,000 elite border troops, it will take at least more than 20 years, and only by replacing them with copper guns can it be completed within four or five years.

He believed that Jiajing would definitely not be willing to wait for more than 20 years, and there would be no problem with the mining of the Chicheng copper mine, but he just didn't know who Jiajing would send to be the mine supervisor.

Next, it will take at least half a month to wait for the mine superintendent, mine the copper mine, and prepare to smelt the bronze, Yang Cong naturally can't be idle, there is no copper mine at this time, and there should be no problem in finding some ready-made copper to make a sample of a new musket first, and he focused on the development of a new type of musket.

Since the front part of the barrel has been changed to copper, the back parts have also been changed to copper, so that the production efficiency will be higher, he pondered for a while, and simply changed the back parts, not only changed to copper, but even added threads or something, and even the front bayonet mechanism he "designed" out.

Originally, he thought that it should be very simple to find some copper to make a sample, but he never thought that a few Yang family shopkeepers sent out, and after looking for a few days, they still didn't find a little copper!

In the end, a shopkeeper had an idea, went to a nearby temple and went around a circle, spent more than ten taels of silver, and bought a scrap copper tripod weighing more than 100 catties.

This copper tripod is used for incense, and I don't know what's going on, there is a gap, Yang Cong looked at the copper tripod in front of him about a foot, and he couldn't cry or laugh.

It's not easy to make something these days.

Fortunately, whether it is a copper tripod or a copper ingot, this copper is finally available, and the furnace for smelting copper ore has been changed by Wang Xuan during this time, as long as the copper tripod is smashed into pieces and thrown into it.

Next is the process of making wood molds, building sand molds, casting, drilling, etc., because of the previous experience, this time Yang Cong does not need to be guided at every step, the craftsmen here are still very professional, as long as they have done it once, they will be, there is no need to repeat training.

This replacement for copper castings is really much easier than iron castings, even if it is three or four feet long barrel drilling holes are not so troublesome, two craftsmen work together, brush brushes, less than an hour to drill the hole, of course, this barrel casting when there is a lot of hole in the middle, not solid, strictly speaking, the back drilling can only be regarded as reaming, if you really drill in a solid copper rod, it is not so easy to drill.

At this time, Wang Xuan also processed the reamer according to Yang Cong's prompts, and the most time-consuming process of inner hole grinding was also solved.

However, at the last step, it got stuck again.

This step is to add a thread between the front and rear two barrels, an external thread, an internal thread, a total of only two threads, if it is in the later generations, even if it is processed with the most backward plate teeth and taps, it is a matter of a few minutes, but at this time, there are no plates and taps, can only be chiseled out by hand, grinding out!

Threads seem simple, but they are not so easy to process by hand, even if they are made of wood, they are difficult to process, let alone copper.

The external thread is better, at least you can see it, it is more convenient to process, the internal thread is different, the angle of view is inconvenient, and the processing is also very laborious, a few skilled craftsmen have been busy for a long time and only the external thread of the front barrel has been processed, but the internal thread of the back barrel they have no way, because the barrel is copper, not wood, and it can't be picked at all!

Yang Cong watched the craftsman use the sharp chisel to try his best to chisel the inner wall of the barrel, but he couldn't do anything, and his brows couldn't help frowning again.

This will definitely not work, even if these craftsmen can find a way to cut out the internal threads, because the efficiency is too low, and the speed of processing threads by hand is simply unbearable, and there is no efficiency at all.

This time, he had to order someone to get charcoal and manuscript paper, draw drawings of plate teeth and taps, and let Wang Xuan find a way to make them.

Wang Xuan encountered the same problem when processing the plate teeth and taps, the tap is easy to say, it is also an external thread, even if it is replaced with iron, it can be processed in a little time, the plate teeth are troublesome, and it is an internal thread, and the copper internal thread cannot be processed at this time, let alone the iron internal thread.

Yang Cong looked at the iron lump that couldn't be picked no matter how he picked it, his head was big, what should I do, this seems to be a dead loop, anyway, I can't process the internal thread on the metal at this time.

He racked his brains and finally came up with a solution, that is, to cut the plate teeth from the middle and divide them into two halves, so that the threads are exposed to the outside, and it is more convenient to process.

In this way, it is easy to process, but the connection of the thread is prone to problems, as long as the thread is slightly misaligned, it will not be screwed in at all.

There is no good way for this Yang Cong, at this stage, he can only rely on the ingenuity of craftsmen to solve this problem.

Not to mention, if it is purely handmade, the craftsmen at this time are much stronger than the craftsmen of later generations, they can even carve lifelike dragons and phoenixes, unicorns or something, and this rigid thread naturally can't help them.

A few old craftsmen pondered for a while, and soon came up with a solution.

In fact, the method is very simple, that is, the teeth on both sides are heated, burned red, and then pressed on the cold tap at the same time, as long as the strength is enough, there will always be traces of threads pressed out of it, and the threads on both sides are basically aligned.

This method cannot be said to be good, but the problem of the plate teeth has been solved, and the difficulties that have stood in front of it have finally been solved, and the production of new muskets can finally be put on the agenda.