Full Metal Jacket

Not the movie or DVD

From Wikipedia, the free encyclopedia.....

"A full metal jacket (or FMJ) is a bullet consisting of a soft core (usually made of lead) encased in a shell of harder metal, such as gilding metal, cupronickel or less commonly a steel alloy. This shell can extend around all of the bullet, or often just the front and sides with the rear left as exposed lead. "

This one is very old and tarnished.