The Heckler & Koch MR556 A4 Upper Receiver Assembly is a premium, short-barreled 5.56 NATO upper designed for exceptional performance, durability, and compatibility with AR-15-style lowers. Featuring an 11-inch cold hammer-forged barrel, this upper incorporates HKs elite-grade craftsmanship and proprietary components to deliver enhanced reliability and precision in a compact format.
Easier approval. $0 Down. Easy installments up to 36 months. Approvals up to $5,000. No hard credit inquires for Pre-Approval. Apply and Buy Today!
Shoot Now, Pay Later® 4 Pay
Pay in 4. Four Payments, no interest for purchases between $150 to $985. No hard credit inquires for Pre-Approval. Apply and Buy Today!
Shoot Now, Pay Later® 4 Pay and Traditional Financing
Try Pay in 4 at 0% interest for purchases between $150 to $985. Or Select Easy installments up to 36 months. Approvals up to $5,000. No hard credit inquires for Pre-Approval. Apply and Buy Today!
This complete upper includes a cold-hammer forged barrel built for extended service life and accuracy retention under heavy use. The HK Free Floating Rail System (FFRS) handguard ensures zero shift with optics and accessories, while the extended convertible charging handle improves manipulation from either side of the rifle.
Also included is the complete MR556 bolt group assembly, engineered to Heckler & Koch's exacting standards for superior performance under adverse conditions. The system is complemented by a tungsten-filled HK proprietary buffer, HK action spring, and adjustable gas block, making it ideal for both suppressed and unsuppressed operation.
Bolt Carrier Group: Complete MR556 Bolt Group Assembly Included
Buffer: HK Proprietary, Tungsten-Filled
Buffer Spring: HK Proprietary Action Spring
Gas Block: Adjustable
Upper Receiver: Forged with Forward Assist
More Information
Barrel Length
11
Caliber
5.56
Condition
New in Box
Finish Per Color
Black
Manufacturer
Heckler and Koch
Manufacturer Part Number
51000385
Model
MR556 A4 Upper Receiver/Barrel Assembly
Type
Uppers
UPC
642230270220
WARNING: This product can expose you to chemicals including arsenic, which is known to the State of California to cause cancer. For more information, go to WWW.P65WARNINGS.CA.GOV
Questions And Answers
Reviews
Due to increased state legislation around firearms, you must be 18 to access our site.
