…legal in America, though some states restrict production of certain things. Yes, you can absolutely make a non-replica, but if you want to actually design your own weapon, I recommend reading Chinn's The Machine Gun which has most of the requisite mathematical details.
弹道模拟可能会是个大方向。关于如何设计机枪和复杂 operating system 这类东西的更多技术文献也会很有帮助，我觉得关于这个主题我读过最全面的就是 Chinn 的《The Machine Gun》了，不过它现在看来挺老的了，没涵盖一些新内容……
Ballistics simulations could be a big one. More technical literature on how to design things like machine guns and complex operating systems would be helpful also, I think the most comprehensive I've read on the subject is Chinn's The Machine Gun but it's pretty old these days and doesn't cover some new stuff.…
……在美国是合法的，虽然某些州对特定物品的制造有限制。是的，你完全可以做一把非仿制品，但如果你真想自己设计武器，我建议读读 Chinn 的《The Machine Gun》，里面涵盖了大部分必要的数学细节。
…legal in America, though some states restrict production of certain things. Yes, you can absolutely make a non-replica, but if you want to actually design your own weapon, I recommend reading Chinn's The Machine Gun which has most of the requisite mathematical details.
弹道模拟可能会是个大方向。关于如何设计机枪和复杂 operating system 这类东西的更多技术文献也会很有帮助，我觉得关于这个主题我读过最全面的就是 Chinn 的《The Machine Gun》了，不过它现在看来挺老的了，没涵盖一些新内容……
Ballistics simulations could be a big one. More technical literature on how to design things like machine guns and complex operating systems would be helpful also, I think the most comprehensive I've read on the subject is Chinn's The Machine Gun but it's pretty old these days and doesn't cover some new stuff.…