There is a lot of debate on the internet about the merits of polymer lower receivers for AR-type rifles. the argument against them is that they are not as rugged or durable as their aluminum counterparts. Proponents assert that polymer lowers are every bit as tough and can be lighter than aluminum.
I am not going to take a side in this debate, but I will say that I have had good experiences with polymer lowers. I have a few friends who have built ARs with both types of lowers, and we have all had good results. My personal opinion is that if you are looking to save weight, go with a polymer lower. If you are more concerned about durability, go with an aluminum one. But ultimately, you decide to make it.
There are a few things to keep in mind if you do decide to go with a polymer lower. First, make sure that you get one from a reputable manufacturer. There are a lot of companies out there that make sub-par products, and you don’t want your lower to be one of them. Second, be sure to follow the instructions that come with the lower. The polymer can be a little tricky to work with, and if you don’t do it right, you could end up with a lower one that is not as strong as it should be.
In short, there are pros and cons to both aluminum and polymer lowers. It is up to you to decide which is right for your needs. Whichever one you choose, just be sure to do your research and buy from a reputable manufacturer.