Hey, guns and ammo is an old science. There has been lots of experimentation. Always seems to come back to the tried and true -- and cheap and reliable.I know brass has all those features. I guess my awe is that there seem to be so few alternatives.
There is a heck of a lot more variation in the actual projectiles themselves -- from basic old lead all the way up to depleted uranium. And shapes and construction -- full/partial/no jacket, fragmentation, expanding, explosive, armor piercing, tracer, etc.