you can knit pick all you want but but AR receivers are sold as pistols to make it legal for you do do whatever you want with it, whether it's build a rifle or pistol as a pistol can be converted back and forth between longarm and handgun but a rifle can not be converted to a handgun.
I am not nitpicking and you are just plain wrong. Don't continue to be ignorant. Look it up. It is there in black and white.