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  • HK 51000385 MR556 Upper Receiver Kit 5.56mm for AR15/M16/M4
Heckler & Koch / H&K UPC 642230270220 MPN 51000385

HK 51000385 MR556 Upper Receiver Kit 5.56mm for AR15/M16/M4

Member pricing
Out of stock
  • Caliber/Gauge .223 REM/5.56 NATO
  • Barrel Length 11"
  • Action .223 REM/5.56 NATO
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Details

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.

Specifications

UPC

642230270220
Manufacturer

Manufacturer Part Number

51000385
Action

.223 REM/5.56 NATO
Barrel Finish

Stainless
Barrel Length

11"
Caliber/Gauge

.223 REM/5.56 NATO
Length

31.1000
Model

MR556 A4 Upper Receiver
Package Height

4.0
Package Width

13.0
Product Type

Accessory-Uppers
Rate of Twist

1-in-7"
Shipping Weight

8.8

Shipping & Returns

All sales are final; we do not offer refunds or exchanges. Items that arrive damaged or defective are covered under the manufacturer's warranty — contact us within 5 days of delivery and we will help coordinate a claim.

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