Using a proprietary aluminum/magnesium alloy, MAG Tactical provides AR-15 upper and lower receivers that are 35-percent lighter than MILSPEC aluminum models. These Gen-4 Ultralite components are a 6,000 series equivalent alloy, as compared to the 7075-T6 aircraft-grade aluminum typically in use, but it's strong enough for the job. The alloy is treated with a proprietary high-phosphorous nickel coating to give it added hardness, and then the components receive the customer's choice of finish and color. This year the company has released a complete rifle built with the Gen-4 receivers and a reduced-weight barrel. We've requested one for a full product review, so stay tuned!