The SIG SAUER MPX is a semi-automatic 9mm pistol caliber carbine with a 16-inch barrel, a folding stock, and M-LOK handguard. It ships with a 35-round magazine. This configuration is listed as QP (qualified purchaser) only, which restricts sale to law enforcement and authorized entities. The MPX platform is a closed rotating bolt design native to 9mm. 
 

Key Specifications 

• Brand: SIG SAUER 
• Model: MPX 
• Caliber: 9mm 
• Action: Semi Auto 
• Capacity: 35 
• Barrel Length: 16 in 
• Color/Finish: Black 
• Stock: Folding 
   

Detailed Features 

• 16-inch barrel keeping the configuration in standard rifle territory 
• Folding stock for compact storage and transport 
• M-LOK handguard for accessory attachment 
• 35-round magazine included 
• QP (qualified purchaser / law enforcement) restricted sale designation

Law enforcement and agency purchasers who run the MPX 16 carbine cite the native 9mm design as a key advantage over blowback-operated alternatives. The closed rotating bolt provides a smoother recoil impulse and is generally considered more tolerant of a wide range of 9mm loads than simpler blowback carbines.

The folding stock configuration is appreciated for storage and vehicle transport. Some users note the folding mechanism adds a touch of play compared to a fixed stock, which is a minor complaint at carbine distances but occasionally noted by those using it as a precision drills platform.

The QP-only sale designation limits the civilian secondary market for this specific configuration, which is a practical note for those considering resale or parts sourcing down the line. Among qualified purchasers, the MPX is generally regarded as a well-built PCC with a track record for reliable feeding and extraction across a range of 9mm ammunition types.