One of the great strengths of the AR-15 platform is the capability for customization, with many parts and accessories designed to simply drop-in. Along with this capability comes the option of building a rifle entirely to one's own specifications, with every part hand-picked for form and function.
American Built Arms' Hybrid AR-15 bolt carrier group is engineered to military specifications, meaning it will fit any upper receiver also designed to Mil-Spec (i.e. pretty much all of them). The Nickel-Boron coated bolt and cam pin extend wear life, and the manganese-phosphate bolt carrier is chrome-lined for extra lubricity.
The NiB-coated bolt is constructed of 158 Carpenter steel, and the bolt carrier is M-16-weight for superior function. The bolt, cam pin and extractor are heat-treated to Mil-Spec requirements, and all components are made in the USA.