Whether you are about to embark on your first AR 15 lower receiver build, or your 10th, there is always a hard decision to make when you are first starting. Choosing what 80% lower you want to start your build with is one of the hardest decisions you will face in this endeavor.
Do you want a Fire/Safe marked lower, billet, forged, unmarked; the list goes on and on when it comes for choosing which AR-15 lower will work best for you and your specific build design.
But no matter what type of lower you decide to go with for your AR-15 build, you will never be disappointed with taking this first step on creating your unique weapon.
When it comes to 80% lowers, there are three material types you will run into while choosing your lower, they are: 6061-T6, 7075-T6, and reinforced polymer.
The 7075 is typically stronger than the 6061 grade material, running about 60% higher in stress and tensile strength. But the simple fact that the 7075 is more rigid, it has a much higher probability of fracturing if it bears a sharp impact as compared to the 6061.
The polymer option has started to become more and more popular because it is so light compared to the 7075 and 6061 options. It is also easier to machine, typically making it a cheaper option. And cheaper can be better in certain circumstances, when you consider the stress AR-15’s put on the lower, if it breaks or cracks, it is much easier and cheaper to replace a polymer part than the heavier metal.
Each one having their own pros and cons, but ultimately, it is up to personal opinion on which one is the superior of the three. In the end it is up for interpretation, and whichever one feels the best to you and your personal build.
There are a few ways that 80% lowers are created, among them are: billet, forged, and cast. Cast lowers have become almost nonexistent, there used to be a lot of problems with them in the past, so they have become a bit taboo, resulting in their practical extinction.Billet and forged are both great options, and again, they comes down to personal opinion for which one is superior.