Sig Sauer 4204140-R Extended Long-Stroke Gas Piston for MCX Spear

The Sig Sauer 4204140-R is an extended long-stroke gas piston designed as a factory replacement component for the SIG MCX Spear platform. Manufactured by Sig Sauer to original equipment specifications, this piston serves as a direct replacement for the factory gas piston in the MCX Spear operating system.

The MCX Spear utilizes a long-stroke gas piston operating system, and this extended variant is built to the same fit and function standards as the original part. It installs in place of the factory piston to restore reliable cycling or replace a worn component, giving MCX Spear owners a factory-direct service part.

Sig Sauer factory part number 4204140-R. Designed to fit the SIG MCX Spear platform.