SIG MCX Piston Assembly – 5.5″ Barrel | 300 Blackout
Not Yet Rated | Write the First Review SKU: 222-SIG-KIT-MCX-PISTON-5B-300
UPC: 799000000000
MFG#: KIT-MCX-PISTON-5B-300

SIG MCX Piston Assembly – 5.5″ Barrel | 300 Blackout (300 BLK)

Built for Suppressed Dominance in Ultra-Compact MCX Builds

Maximize the performance of your ultra-compact SIG MCX 300 BLK platform with the SIG MCX Piston Assembly for 5.5″ barrels—a precision-engineered, factory-original component crafted for short-barrel, high-efficiency gas operation. Whether you're running suppressed or unsuppressed, this OEM piston system is specifically tuned for the unique pressure and timing demands of sub-6" 300 Blackout builds.

This assembly ensures reliable cycling, reduced fouling, and consistent gas regulation, especially in SBR or PDW configurations where timing is critical and space is limited.

🔧 Key Features:

• ✅ Factory OEM from SIG Sauer – Designed to match factory specs for maximum reliability and safety.

• 🎯 Tuned for 5.5″ 300 BLK Barrels – Ideal for suppressed or short-barrel MCX configurations.

• 🔇 Optimized Gas Flow – Ensures smooth cycling even with subsonic ammo or suppressor use.

• 🧱 High-Strength Construction – Machined steel, black finish, built to handle extreme temps and carbon buildup.

• 🔁 Drop-In Replacement – Keeps your MCX running clean, quiet, and consistent—just like new.

What’s Included:

• Complete Piston Assembly for SIG MCX with 5.5″ barrel in .300 AAC Blackout

⚠️ Important: Does not include barrel, upper, or gas block components. Intended as a factory replacement part.

Technical Specs:

⚠️ Installation & Safety Warning:

This part requires disassembly beyond field-stripping. SIG Sauer requires installation by certified armorers only. Improper installation can result in malfunction, serious injury, or death. Substitution of parts is not advised. Warranty coverage may be voided by unauthorized installation.