Product Features & Specifications

HK 51000384 MR556 Upper Receiver Kit 5.56mm for AR15/M16/M4

This kit includes a complete upper receiver/barrel assembly, allowing Mil-Spec 5.56mm AR-style rifles to be retrofitted to HKs 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.

Upper will ship in HK Soft case.

Brand	HK
Series	Upper Receiver Kit
Model	MR556
Caliber	5.56mm
Firearm Fit	AR15 / M16 / M4
Color	Black
Length	16.50"
SKU	178700
UPC	642230270213
MPN	51000384