Heckler & Koch MR 556 A1 Rifle

Posted: 09/25/2025

Heckler & Koch MR 556 A1 Rifle

The Heckler & Koch MR556A1 is a semi-automatic, 5.56x45mm NATO rifle featuring a 16.5-inch cold hammer-forged barrel with a 1:7″ twist. It utilizes a piston operating system, weighs approximately 8.6–9.1 lbs, and has an overall length of 33.9 to 37.68 inches. The rifle includes a free-floating rail, 30-round capacity, and a two-stage trigger.

Specifications:

  • Action: Semi-automatic, Piston-operated
  • Caliber: 5.56 x 45mm NATO
  • Barrel Length: 16.5 inches (420 mm)
  • Barrel Profile: Heavy profile, cold hammer-forged, 6 lands & grooves, 1:7″ RH twist
  • Overall Length: 33.9 inches (collapsed) – 37.68 inches (extended)
  • Weight: ~8.6 lbs – 9.1 lbs
  • Magazine Capacity: 30 Rounds (standard)
  • Trigger Pull: ~7.64 lbs (two-stage)
  • Stock: 6-position retractable stock
  • Handguard: Free-floating rail system
  • Finish: Black