HK MR556A1 5.56mm 16.5" Complete Upper Receiver Group Kit

Out of stock
as of 07/16/2024 3:51AM CST
Store Inventory
Available OnlineOut of stock
Fountain Valley, CAOut of stock
The Colony, TXOut of stock
SKU: HK-81000584
MPN: 81000584
UPC: 642230262607

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Based off the HK416, the civilian MR556A1 uses the HK proprietary gas piston operating system, employing a piston and a solid operating “pusher” rod in place of the gas tube normally found in AR15/M16/M4-style firearms. This method of operation virtually eliminates malfunctions that are common to direct impingement gas systems since hot carbon fouling and waste gases do not enter the receiver area. This is the same key feature critical to the success of the HK416 rifles used by leading military and law enforcement customers. 

The MR556A1 complete upper receiver is produced in the USA using German made components. The upper uses a German made cold hammer forged, un-chromed barrel for superior accuracy and longevity. The MR556 upper includes the HK FFRS free-float handguard with M-LOK compatibility.

The MR556A1 upper receiver includes bolt, buffer, buffer spring.

Caliber 5.56 NATO
Operation Gas Piston
Barrel Length 16.5"
Barrel Features Cold Hammer Forged, Non-Chrome Lined, Heavy Contour
Twist 1:7" 6 Grooves
Handguard HK FFRS, M-LOK
Upper Receiver HK MR556
Buffer HK Tungsten Filled
Buffer Spring HK Proprietary
Bolt Carrier Group HK Complete MR556

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