Sig Sauer MPX 9mm Caliber Exchange Kit 4.5" Barrel Gen II

The Sig Sauer CALXMPX4B9G2 MPX Caliber Exchange Kit transforms your MPX platform into a 9mm Luger configuration with precision engineering and drop-in simplicity. This factory conversion kit delivers the versatility shooters demand from their MPX system. Built to Sig Sauer's exacting standards, it maintains the platform's legendary reliability while expanding caliber options.

What Makes This Different

Unlike aftermarket conversion solutions, this OEM caliber exchange kit integrates seamlessly with MPX Gen II receivers without modification or fitting. The black nitride finish provides superior corrosion resistance compared to standard phosphate coatings, extending service life in harsh environments. Factory engineering ensures headspace specifications meet SAAMI standards for consistent performance and safety.

Key Features

• 4.5-inch carbon steel barrel with black nitride finish for enhanced durability
• Integrated flash hider reduces muzzle flash and signature
• Drop-in installation compatible with all MPX Gen II receivers
• Factory headspaced for optimal accuracy and reliability
• Maintains original MPX operating system and controls
• Compatible with standard 9mm Luger ammunition
• Retains full-auto rated bolt and operating components

This caliber exchange kit excels in multiple roles from competition shooting to professional applications. The 4.5-inch barrel length provides an optimal balance of velocity and maneuverability in close quarters. Law enforcement agencies appreciate the commonality with sidearm ammunition, while competitive shooters benefit from reduced ammunition costs compared to rifle calibers. The nitride treatment resists fouling buildup during high-volume shooting sessions.

Technical Specs

• Caliber: 9mm Luger
• Barrel Length: 4.5 inches
• Barrel Material: Carbon steel with black nitride finish
• Muzzle Device: Flash hider (included)
• Compatibility: Sig MPX Gen II receivers only
• Thread Pitch: 1/2x28 TPI
• Country of Origin: USA
• Manufacturer: Sig Sauer

This factory caliber exchange kit represents the most reliable method to convert your MPX platform to 9mm configuration. Sig Sauer's engineering expertise ensures proper timing and headspace for consistent accuracy. Professional armorers and serious shooters choose OEM components for mission-critical applications where reliability cannot be compromised.