The lack of weapon materials was still a headache.
Most of the metal materials in the Heaven's Wall city's storage were used to make guns and cannons, and the stock was getting smaller and smaller.
For example, the underground tomb that was previously discovered had basically been emptied out after a period of moving.
The remaining metal materials were all shockingly large, and it was impossible to complete cutting and moving them in a short time.
With no other choice, he could only choose to give up.
The two mountains near the Heaven's Wall city did have iron ore, but the primitive mining efficiency was too low to meet the needs of weapons.
Perhaps after a while, the metal materials would be completely used up, and the weapons could no longer be produced.
Of course, this matter would be left to Tang Zhen to worry about. With the methods he had, he would be able to find a solution to the problem.
