The EXO ONE (X01) is a patent-pending multi-caliber exoskeleton for the Sig Sauer® P320 Fire Control Unit (FCU) and adjacent firearm components including barrel, slide assembly, and magazine release. This transformation happens in moments without tools and is fully reversible.
The X01 standard model can be chambered in 9x19mm Parabellum, .357 SIG, and .40 S&W by transplanting the corresponding P320 components (.45 ACP is in development, as the changes in magazine well dimensions require a specialized lower receiver). The X01 body is injection-molded in the US with glass filled nylon.
The rear of the lower receiver features a vertical M1913 Picatinny rail for integration with SIG® MPX//MCX buttstocks and arm braces, such as models manufactured by SIG® and SB Tactical®. This rail can also adopt a sling attachment for outward tension stabilization, a non-shouldering cheek rest, or be left empty for concealed carry.
The X01 features an upper/lower receiver construction that attaches via the forward receiver hinge and is locked in place by a rear recoil spring guide. Models equipped with a dual-rod buttstock or arm brace will also lock together via two guide rod channels that span both the upper and lower receiver for added stability.
The upper receiver features shell deflection ramps to mitigate malfunctions. Steps to clear a malfunction are identical to the P320 with the exception of working the action via the charging handle rather than the slide itself. The upper receiver was designed to accommodate suppressor iron sights.
The non-reciprocating charging handle locks the action open (the slide to the rear) with an upward motion when fully retracted. The action can then be released with a downward motion (akin to HK-style weapon systems). In addition, if the charging handle is in the forward position, the slide can be released via the FCU slide release during reload procedures.
The X01 features three M-Lok slots near the muzzle for accessory and grip attachments. The upper receiver features a 19-slot milspec M1913 picatinny rail. Pistol/rifle backup iron sights (BUIS) are suggested for co-witness capability with low profile optics. The lower receiver features dual quick-detach (QD) points.
The X01 was designed with ergonomics in mind and features an integrated angled foregrip with a substantial hand stop hook to prevent the support hand from slipping in front of the muzzle during dynamic weapon manipulation. Additional hand stops and grip accessories can be attached via the M-LOK® slots for a custom ergonomic interface. All components of the X01 are manufactured in the United States.