Because of its small calibre the AR15 type weapons are nowhere near as Lethal as your great grandpappy's deer rifle. Fortunately spree shooters are usually as ignorant of Ballistics as tv "news" characters. .556 or .223 are hot .22s. You can't use em in most states to hunt deer.
The majority of gun deaths are suicides. Over 1/2. Of what's left over half are crooks shot by cops, other crooks or victims. Giving you less people a year dying from gunshot wounds than die from automobile accidents caused by cell phones.
The meme isn't about handguns. It IS about irrational people and their fear of scary black guns that account for less than 3% of murders committed with guns.