Think of the word “steel.” Lot’s of things might come to mind...a steel mill, an I-beam, a fork, and, if you’re on this site, body armor. But all of these types of steel can be of very different grades, and that’s why it’s important that the steel you put into your armor plate carrier is the right grade — AR500.
AR500 is ballistic grade steel. Melting down a bunch of forks and sticking them into your Condor isn’t going to work...you need steel that measures a hardness of at least 500 on the Brinell Hardness Scale… and that’s where the number in the AR-500 body armor plates comes from. AR-500 is at minimum a 500, and specifically made to be as light as possible while retaining this hardness. (Mild steel rates about 120 on the scale.)
Of course, there are harder steels than AR-500, but you’re really never going to need that. After all, it’s not often that you’re going to need something to stop more than a 30.06, and if you are hit by something larger than that, then no steel in the world is going to help you (unless you’re carrying a tank on your back).
Design also matters, no doubt abou that. The strike face has to be properly curved in order to produce as much shock absorption as possible so that fragmentation doesn’t become a problem.
So unless you have a few million dollars to drop on a rhenium diboride vest (which would be amazing...can we borrow it?), AR-500 is probably the way for you to go. Check it out here.