The weapon tycoon who traveled to Daqin

The historical collector's uncle, who keeps an ancient secret and, for reasons of childlessness, wishes his nephew to inherit it.
But the nephew has no interest.He is only interested in developing weapons.More new weapons.Earn more banknotes.This is his only pleasure.
However, in the process of passing on this ancient secret, an accident appeared.Nephew crossed over.
Came to the end of the Warring States period.
Hey, if you come here, you will be safe. I am a weapon expert. Isn't it easy to deal with cold weapons?
You have cavalry, I have machine guns, you charge, I will lay mines, pull barbed wire, you run, I am an expert.There are tanks and armored vehicles on the ground, and airplanes in the sky.Surrender.
What are you waiting for mechanized weapons to be used on ancient battlefields...