研发新装备太平洋战争爆发后，日军的战线越拉越长，后方供应难以为继，在华的日军也开始回收旧弹壳了。我方能收集到的旧弹壳越来越少，即便有了自制的无烟药，也无法扩大子弹的产量。形势迫使我们加紧研制新弹壳。边区铜的来源全靠收集起来的制钱和杂铜。它们含的杂质太多， R & D of new equipment After the outbreak of the Pacific War, the Japanese military’s longer and longer front, the supply is unsustainable rear, the Japanese in China began to recover the old shell. We can only collect fewer and fewer old shells, and even with our own smoke-free drugs, we can not expand the production of bullets. The situation forced us to step up the development of new shells. The sources of copper in the border area depend entirely on the collected money and miscellaneous copper. They contain too much impurities,