倍投法则必输

简介：Jiao Xu and Li Shun personally conducted cannon testing to test the power of the small bronze cannon. The target was a wooden shield car placed at 250 paces. Zhu Cixiang clearly saw that Jiao Xu was proficient in using a gun ruler and a measuring board. Although Li Shun also used these two tools, it was only for reference. He mainly relied on visual inspection.