80% Lower Receivers

Source: https://www.ar15part.com/product-p/80pflr-15.htm

Introduction:

One of the unique aspects of American culture is our gun culture. Firearms enthusiasts and hobbyists have existed in the United States since its founding. We also have a unique distrust of government. The United States was founded through revolution against autocracy and the mindset of fighting tyranny has permeated into the culture today. I believe that few things exemplify both of these things more than the 80% lower receiver. Much like what enthusiasts and makers have done with 3D printers, 80% lowers seek to render gun control obsolete.  

Details:

The idea of an 80% lower receiver is that a prospective firearm owner can purchase a lower receiver that is 80% completed, machine out the other 20%, and then have a lower receiver without having to go through a background check. The 80% lower, especially for an AR-15, is incredibly popular because they are unregulated. Because they're not completed lower receivers, they are regulated the same amount as any other piece of aluminum or polymer.

Source: https://www.80-lower.com/blogs/80-lower-blog/do-i-need-an-80-lower-jig-to-build-an-ar-15/

So in order to machine an AR lower correctly, ideally you'd have a milling machine. Luckily, for those of us who aren't machinists, companies have designed a variety of jigs that reduce the number of needed tools to pretty much just a drill press and a router. This brings the potential to have an AR-15 to anybody with the mechanical aptitude and the drive to make one. Because the lower receiver of an AR is the only regulated part in the US, someone could theoretically have all the necessary supplies to build a functioning firearm shipped to their door. The 80% lower trend has also expanded beyond just AR-15s 

Source: https://www.uspatriotarmory.com/Patriot-G19-80-Pistol-Build-Kit-With-Threaded-9mm-Barrel-Polymer80-PF940C-Gray-p141021080

Glock 80% frame kits have become wildly popular because much of the time, they only require things like dremels and hand drills to finish. These pistols, in my opinion, are more interesting than 80% AR builds because they can be built by people with very few tools and used to defend themselves, independent of regulation. Because pistols are typically more regulated than rifles, 80% pistol frames effectively negate all regulation. They are perfectly legal to build in the US if done correctly, but they retain potential to help bring firearms to people in a way that is effectively untraceable.

Use:

Although home-built ARs have shown up now and again, one interesting story revolves around a pistol built on an 80% lower that was recovered by police in Hong Kong, where pro-democracy protests have brought the city to the streets.

Source: https://www.scmp.com/news/hong-kong/law-and-crime/article/3041132/hong-kong-police-seize-weapons-including-handgun-ahead

This is interesting to me because Hong Kong has extremely strict gun regulations. According to the news story, anti-China radicals may have been planning to use the pistol against Hong Kong police during the latest round of large-scale protests. Now I do not condone unnecessary violence, I am more interested in what the presence of this gun represents. This gun was able to get into a city that is more and more under the thumb of one of the most oppressive regimes on Earth. I'm not sure whether or not it was built in Hong Kong, but it would not surprise me if a 80% polymer lower was brought in as an airsoft accessory, since airsoft is popular in Hong Kong. After this, it was built by a pro-democracy radical into a functional firearm. 

Conclusion:

80% lower receivers function similar to 3D printers when it comes to firearms. It puts the potential for firearms manufacturing into the hands of normal people. This creates a situation in which people are no longer reliant or subject to government regulation. For many states, regulation is fairly mild, so 80% lower receiver builds likely are less common because it is easier to just go out and buy a gun or buy a lower. However, in states that have more strict regulations, such as states or municipalities that limit possession of certain firearms, an 80% lower gives motivated people the ability to manufacture their own firearm and skirt government regulation. And whats more American than that?