The HK MR762 A4 is an AR-10-pattern pistol chambered in 7.62x51 NATO with a 13-inch threaded barrel and a 20-round magazine. It uses an M-LOK handguard and ambidextrous controls. The receiver is finished in black. 
 

Key Specifications 

• Brand: HK 
• Model: MR762 A4 
• Caliber: 7.62x51 NATO 
• Action: Semi Auto 
• Capacity: 20+1 
• Barrel Length: 13 in (threaded) 
• Color/Finish: Black 
   

Detailed Features 

• 13-inch threaded barrel in 7.62x51 NATO 
• M-LOK handguard for accessory attachment 
• Ambidextrous controls 
• AR-10 platform pistol configuration 
• 20-round magazine included

Owners of the MR762 A4 consistently point to build quality as the main reason they chose it over other AR-10 pistol configurations. The fit and finish meet expectations for the HK brand, and the 7.62x51 NATO chambering with a 13-inch barrel is considered well-suited to its role.

Ergonomics and handling draw mixed feedback. The weight is noticeable, and the 13-inch barrel in a pistol configuration means muzzle blast is something shooters manage rather than ignore. The threaded barrel and M-LOK rail give flexibility for adding a suppressor or forend accessories.

Value is the consistent sticking point. The MR762 A4 carries a premium price, and owners debate whether the HK name alone justifies the cost over competing AR-10 pistol builds. Aftermarket support is decent but not as broad as standard AR-15-pattern platforms, which some find limiting over time.