You learn something new every day.
Thank you,
You know what really surprised me when I first learned it? How a .30-06 deer rifle can punch a complete hole through a 4" steel (galvanized) pipe, set up 30 yards from the rifle. And then the bullet keeps going. On the same pipe, a 357 Magnum revolver barely made a dent from the same distance.
Next to that galvanized pipe, a "bulletproof vest" is a t-shirt to a real rifle caliber.