It's more fun than playing "Maybe baby" because you don't have to wait a few months after you shoot your load, you find out immediately!
I know for a fact, that a 5.56 round will not chamber in a AK74... thank God it wasn't the other way around. Now, I only shoot brass 5.56.
I was never impressed with the Steel cased ammo in. 223 it's shot groups looked like rat shit in a dresser drawer.