The Sig Sauer 4204140-R Ext Piston Long Stroke MCXSpear is a dedicated factory piston assembly designed to keep your MCX Spear running smoothly and reliably. Built to Sig’s exact specifications, this long-stroke piston is engineered for consistent gas regulation and dependable cycling when paired with compatible MCX Spear platforms.

This model is ideal for shooters who want to maintain factory performance on their MCX Spear or replace a worn piston with an original Sig component. Whether you spend most of your time on the range or in structured training, this piston helps preserve smooth operation and consistent recoil characteristics. It reflects Sig Sauer’s focus on precision engineering and durable firearm components.

Key Features:

• Manufacturer: Sig Sauer
• Model: 4204140-R Ext Piston Long Stroke MCXSpear