A pointless thread IMO, and in majority inaccurate or besides the point postings, if I may say so.
It isn't about the AR-15 "looking" like a military weapon or Assault Rifle - but that a semi-automatic weapon (that in it's standard version, is already able to produce a higher firing rate then e.g. a single bolt action rifle), is very easy to purchase - and can be turned into a fully automatic weapon, simply via a respective Bump Stock.
These bump stock devices are AFAIK 100% legal (a semi-automatic rifle equipped with one is still not classified as an automatic weapon), Combine e.g. a bump stock modified AR-15 with a 100-round magazine and essentially you have a full-fledged machine gun in your hands.
It's a technical legal loophole - that IMO needs to be handled accordingly and that in general, magazines - holding more then 10 rounds shouldn't be allowed outside of a shooting range. - just my 2 cents.