[Vincent_Yan404]

As far as I know, yes. The most critical component—the Uranium-235 core—was finished in 404. In Part I, I mentioned a legendary machinist named Yuan Gongpu. He was tasked with the final precision turning of the core on a lathe.

It’s famously known as the 'Final Three Cuts.' Because the material was so rare and the stakes so high, he had to complete the final shaping in three extremely delicate stages. He achieved a precision of 0.001mm (often described as 1/80th of a human hair) entirely by hand. This earned him the nickname 'Yuan the Three-Cuts' (Yuan Sandao) in our hometown history