Core77

Metal production method examination time: Samurai swords vs. bullets! Both involve one type of metal wrapped inside another, and are designed for similarly ignominious purposes.

For samurai swords or katana, the swordsmith heats and folds the outer shell into a U-shape, then fits a softer metal into the groove and bonds them together. Before being joined, both layers are folded and rehammered numerous times for strength. The hard outer shell is razor-sharp, and the softer, more flexible core lets the sword withstand impacts a singular, brittle piece of metal couldn't.

With bullets, lead is extruded, cast or swaged into slugs, which are then wrapped in copper or nickel "jackets" much harder than the relatively soft lead within. The lead provides the heavy mass and momentum, whereas the harder jacket enables it to slice through the air.

So which is stronger?

Turns out if you fire bullets at a katana, the katana actually cuts the darn things in half:

Note to all the samurai and heavy machine gun teams reading this: please don't try this at home.

via tv in japan