Another military sourced rifle that needs banned:
https://d262ilb51hltx0.cloudfront.net/max/800/1*FPvQViQ36NuU2DGjOhiruw.jpeg
Virtually every single gun can be traced back to military use, back to flintlocks.
So what?
Modern firearms are specialized, purpose built. They have different features depending on that. The M16 in all its variants was built to kill a lot of people in a short period of time which explains its features. It is an extremely well designed firearm in that respect. The AR 15 is just one variant built to satisfy the law wrt semi-auto firing exclusively.
Mexican cartels, terrorists & nutjobs buy them for that purpose. They're not really much good for anything else other than shoot 'em up fun & self defense fantasy.
While the Constitution affirms the right to bear arms the right of the people to reasonably restrict the kinds of guns available to civilians is well established. If all the AR15 variants disappeared from gun stores tomorrow there would remain literally hundreds of others not nearly as well suited for mass murder.