The Flux Raider is a chassis system designed to turn the SIG P320 into a very compact PDW. The design concept began as a desire to improve the practical accuracy of a handgun by adding a collapsing stock while keeping the weapon holsterable. Flux' first product, circa 2019, was a spring-loaded stock that could be attached to the back of a Glock pistol. This had some clear shortcomings, and it led to development of the MP17 in 2020. This was a SIG chassis, something made feasible by the use of a serialized fire control group in the P320 pistol. The MP17 used the same basic stock design as the original Flux brace, but added an optics mount and a space to store a space magazine.

Less than 400 MP17s were built before the design was refined into the Flux Raider, and the manufacturing changed from printing to molded polymer. Of particular significance was the choice of polymer compounds to use, as the typical glass-reinforced nylon is not rigid enough to keep a good optics zero. By opting for a much more rigid material (albeit a much more expensive one), Flux was able to remove the metal reinforcing in the chassis, lightening the system while still retaining an optics mount stable enough to hold zero under adverse conditions. The spare magazine system was also significantly improved in the Raider, and an ambidextrous manual safety added.

Today, Flux has partnered with SIG to produce the P320 Flux Legion. I am excited to see where Flux and SIG take the design from here!