AR-15 rifles are high performance firearms that are legally available for civilian use. The firearm is designed to be magazine-fed and lightweight. It comes with several parts that can be disassembled.
Each of its part is important to deliver the kind of performance with which it was design for. The lower receiver is especially critical in its operation because it is the base of the rifle. The parts can be replaced individually so an upgrade to any of its part is possible at any given time.
The lower receiver is available in different materials. As long as it is designed to work with MIL specified standards, the lower receiver should be compatible with AR-15 rifles of any build. Earlier versions of the rifle are made of metal because of the need for a sturdy base. Aluminum is the metal of choice for it to be as light weight lower as possible. As years went by, newer and better materials are being developed to further improve the performance of the firearms.
In order to maintain the lightweight firearm design, the new materials have to be equal or lesser than aluminum in terms of weight. This is highly critical in ensuring precise and accurate firing.
At first, polymers were used to create lightweight lower receivers instead of metal. While its weight has definitely decreased, this approach did not effectively replace metal lowers because of performance issues. Although the new material made the firearm easier to handle, it affected its performance and reliability.
Lightweight lowers are ideal for rifles so it can be handled and aimed with ease. However, with polymer or plastic, the quality lower receivers are so poor that it made the rifle hardly worth using at all.
After careful consideration, gun parts manufacturers found a way to incorporate the benefits of polymer, being an extremely lightweight material, with the strength and durability of other materials. This gave birth to a composite lower- a combination of more than one material. Composite materials made it possible to achieve lightweight lower receivers with good performance.
Among the several types of composite lowers, carbon fiber composites are most notable due to its strength that has been tried and tested in other manufacturing industries like modern jets or car chassis. Carbon fiber is also known for its lightweight as it weighs less than an aluminum by half.
The use of composite lower receivers may be relatively new, because only a few manufacturers dared to do the impossible. Yet, it has a promising potential in the near future.