I’ll be honest, knowing about firearms made me think that this was a clear cut answer that should be obvious to everyone; an AR-15 is not an assault rifle. However, the more I looked into this, the more ambiguity I discovered.
First of all, as iraqveteran8888 pointed out, there is a lot of ambiguity surrounding the word “assault” itself when referring to firearms. Eric from that channel describes it as giving an action to an inanimate object before any human interaction is even involved, and I tend to agree with him on that. By saying that it is an assault rifle, you insinuate that its intended use is to assault, which is somewhat problematic because that is not the use of the AR-15.
Second, most people believe that the AR in AR-15 stands for “assault rifle” or “automatic rifle”, but it does not. It stands for Armalite rifle, Armalite being the company that designed it.
Third, all of the laws, new and old that the ATF has surrounding some of the more popular rifles, such as the AR-15 are very confusing. For gun owners, the term assault rifle will most likely mean a lightweight, somewhat compact, fully automatic military rifle, such as an M4, HK416, etc. According to the NFA (National Firearms Act) under the ATF, such fully automatic firearms are classified as machine guns, where multiple shots are fired for only one pull of the trigger. Since the AR-15 only has one shot fired per trigger pull, most gun owners and dealers would consider it to be a semi-automatic sporting rifle. However, the media has a nature to try to hype things up and will use the term assault rifle or assault weapon when referring to an AR-15 in order to attract attention. Aside from the media demonizing this rifle, the ATF has done its job playing into this as well. As part of what is referred to as the “Clinton Ban” (The massive ban on specific types of firearms and accessories from 1994-2004) was the SAW (Semiautomatic Assault Weapons Ban). Under this legislation, the AR-15 is considered an assault rifle if essentially, any accessory was added to it. However, this legislation expired in 2004.
Now, the defining element for most people determining if the AR-15 is an assault rifle or not is the definition of assault and if you believe that it applies to the AR-15. Most dictionaries describe assault rifles as being fully automatic and used by the military, none of which apply to the AR-15. For me, the ultimate decider of this question would be the ATF. I have spent hours trying to look up the ATF definition of assault rifle, and trying to see how they classify the AR-15 as an assault rifle, but I came up empty handed. If anyone can find either of those, I would greatly appreciate it if you left the links in a comment. However, since the AR-15 is not listed in any provisions of the NFA that I have found, I believe that it is not an assault rifle, but the topic is definitely still open to much discussion.