Overview
This kit includes a complete upper receiver/barrel assembly, allowing Mil-Spec 5.56mm AR-style rifles to be retrofitted to HK’s piston and pusher rod system. This system utilizes a piston and a pusher rod in place of the gas tube normally found in AR15/M16/M4-style rifles. This closed system virtually eliminates the malfunctions that are common in direct-impingement gas systems, since hot carbon fouling and waste gasses are not propelled into the receiver area to operate the action. This is the same key feature critical to the success of the HK416 used by elite military and law enforcement customers.
- Complete MR556 A4 Upper Receiver/Barrel Assembly— HK cold-hammer forged barrel, upper receiver with forward assist, extended convertible charging handle, HK Free Floating Rail System handguard
- Complete MR556 Bolt Group Assembly
- Tungsten Filled HK Proprietary Buffer
- HK Proprietary Buffer (Action) Spring
- Adjustable Gas Block
- Ships in HK Soft case.
- NOTE: The MR556 A4 Upper Receiver Kit is not classified as a firearm and can be purchased without a Federal Firearms License ( FFL).
Specifications:
- Caliber: 5.56mm
- Color: Black
- Upper Receiver: Forged, HK MR556A4
- Bolt Carrier Group: MR556A4
- Rail: MLOK
- Barrel: 11″ Cold Hammer-Forged Barrel, 1:7 Twist
- Gas System: Short-Stroke Gas Piston
- Gas Block: Adjustable
- Charging Handle: HK Ambidextrous
- Muzzle Device: Birdcage
- Buffer Assembly: HK Heavy Buffer
NFA DISCLAIMER
This Item is regulated by the National Firearms Act (NFA). Please check with your local and state municipalities for any further regulatory requirements. It is the buyer’s responsibility to make sure they comply with all NFA rules and applicable laws. If you need further information on NFA regulation, please contact an attorney.
