SIG KIT-MCX-PISTON-16B-556 is the factory MCX piston assembly for a 16-inch barrel in 5.56 NATO. While more than one piston kit is offered, this listing is for 5.56, 16-inch only.

The kit is steel, finished black. It includes the selector valve and the piston rod. It sits on top of the barrel in the gas block. SIG wants a certified armorer to install it; this is past a field strip, and the parts go in as a unit.

This listing is the SIG MCX 16-inch 5.56 piston assembly only.

• Manufacturer: SIG SAUER — MCX piston assembly, KIT-MCX-PISTON-16B-556
• Fit: MCX; 16-inch barrel; 5.56 NATO
• Contents: selector valve; piston rod
• Build: steel; black
• Install: armorer; as a complete unit
• This listing: 5.56, 16-inch piston only