Took this with permission, from an eloquent Lawyer friend of mine. Let's all get on the same page.
" If we want to ever make progress towards adequate gun control laws in the United States, we're going to have to stop calling for "assault rifle bans." That's a near-constant refrain, and it nearly constantly causes pro-gun people to instantly stop listening to everything else that follows, because they're going to immediately pivot to one of two claims: (1) "there is no such thing as an 'assault rifle' (false) and you're just scared of the aesthetics of the weapon;" or (2) "assault rifles are already illegal, and all of the weapons you don't like are just semi-automatic rifles" (better).
There is actually a legitimate definition of an "assault rifle," which is "a rifle with selective-fire capability that uses an intermediate cartridge and a detachable magazine" -- it has three criteria: (1) selective fire, (2) intermediate cartridge, (3) detachable magazine. Generally speaking, selective-fire weapons, and therefore actual assault rifles, are already illegal to own in the United States. The average person can't go to his local gun shop and buy one. Acquiring one requires filing a federal application and completing an extensive approval and registration process; they can't be sold or otherwise transferred to another owner without permission from the ATFE; and they can't have been manufactured any more recently than 1986.
Advocates for adequate gun control laws in the United States would be speaking more accurately and would thereby gain credibility with those whom they seek to convince if they focused on the detachable-magazine aspect rather than incorrectly using the term "assault rifle" to refer to rifles that differ from actual assault rifles only in that they are semi-automatic instead of selective-fire. The issue is the ability that detachable magazines give to fire numerous rounds quickly and reload quickly, which isn't necessary in any context other than killing people.
What we should be doing is making it illegal to own semi-automatic rifles with detachable magazines, because if I'm hunting, a bolt-action rifle is more than adequate (in fact, one with a 5-round detachable magazine is probably adequate for that, but I could see why ranchers or someone defending livestock against wildlife might want a bolt-action with a larger magazine capacity than 5 rounds). And if I'm looking for personal or home self-defense, a rifle isn't even close to my best option; both handguns and shotguns are better suited to that purpose than rifles.
Of course, many pro-gun people will still disagree with the above position. However, we won't be giving them the ammo (so to speak) to just derail the entire argument and stop listening the minute we incorrectly classify something as an "assault rifle." Instead, they'll have to engage in the actual, legitimate discussion about whether semi-automatic rifles and/or detachable magazines on rifles are necessary for peaceable purposes. They'll have to explain why they can't adequately hunt with a bolt-action rifle or defend themselves with a handgun or shotgun. From there we can maybe move on to more nuanced arguments about magazine size, whether semi-automatic weapons are necessary at all, arguments about various accessories, etc. But we'll never get past the first sentence as long as we keep talking about "assault rifles."
If we want to get anywhere, we have to speak like we know what we're talking about. "