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Building an AR-15: FAQ Part 2

18th Apr 2016

In our last blog, we went over three commonly-asked questions about building an AR-15. Whether you are building your first AR, or you build them as a hobby, staying on top of the basics is extremely important. Today, we are going to answer two more common questions that people run into when building an AR for the first time.

  1. I am confused by the term “barrel twist” and the ratios that come with it. What does it mean?
    • Firstly, the ratio refers to how many inches the bullet will travel in order to spin once. For instance, a 1:7 ratio means that, as the bullet travels down the barrel, it needs to travel seven inches to make one complete spin.
    • You need the barrel twist ratio that will work with the type of ammo you want to use. You will be choosing between a 1:7 ratio and a 1:9 ratio. Basically, the 1:7 can shoot lighter and heavier rounds well. The 1:9 ratio shoots light rounds very well and doesn’t perform as well with heavy rounds, especially at long distances.
  2. I need to choose a barrel. What do rifle length, mid-length, and carbine mean?
    • These terms refer to the location of the barrel’s gas port. It needs to be compatible with the gas tube you choose.
    • Generally, mid-length and carbine systems work on 16-18 inch barrels. If you have a barrel that is 20 inches or longer, you will want a rifle system.

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