Amazing the amount of research and design...
....that goes into something that in 99% of armed battles just means "throw as much noise, chaos and lead down range at the other guys in the hope they give up or run away first!"
Studies after the Korean War found that past 50m you were just as likely to get hit by a stray bullet or shrapnel than you were an actual aimed bullet. It's not about accuracy in most cases, its about ripping up whatever you hit, aimed or otherwise, as much as possible.
Not that I'm saying I wouldn't want better bullets in my weapon to spray downrange.