All posts by William Larson

Will Larson is a veteran of the U.S. Army Infantry and the U.S. Coast Guard where he served as a Gunner's Mate. After leaving the military with almost 10 years of military service he entered into the world of contracting working primarily in Iraq and Afghanistan for 6 years. He is the owner/instructor for Semper Paratus Arms, LLC which teaches AR-15 based armorer and builder courses and he is the master armorer for SIONICS Weapon Systems in Tucson, Arizona. He has completed numerous factory and field armorer courses and a variety shooting courses and has close to 30 years of experience with the AR-15 family of weapons.

Understanding the AR-15 Gas System

The AR-15 Direct Gas Impingement System is a rather straight forward system to understand. When the weapon is fired, gas travels down the barrel behind the bullet. As it passes the gas port, it is diverted into the Front Sight Base (FSB) or Gas Block into a gas tube which carries it into the bolt carrier key. Once the gas arrives at the key, it dumps the gas into a chamber causing the bolt carrier to move rearward.                                              (Elements of the gas system) Gassing starts in the chamber with the round of ammunition. This means that ammunition selection is important. Ammunition may be loaded to either .223 specs or 5.56 NATO specs. Ammunition produced with poor quality control can affect the operation of the weapon. From here we move to the gas port. The gas port is very important to the overall function of the rifle. In the military world this is virtually a non-issue since gas ports are standardized. In the commercial/civilian world a manufacturer can gas their barrel anyway they want. One of the first things


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