HK MR556 A4 Pistol – 5.56, 11" Barrel, One 30-Round Magazine (81001050)
HK lists this as a pistol, and that is what it is: the MR556 A4 with an 11-inch barrel in 5.56 x 45mm, one 30-round magazine, a short-stroke gas piston, and fully ambidextrous controls. HK ID number 81001050, UPC 642230269439.
This listing is for the MR556 A4 pistol, 5.56, 11-inch barrel, one 30-round magazine only. It is a pistol, not a rifle.
Short-Stroke Piston
The MR556 A4 is HK-USA's commercial take on the HK416. The short-stroke gas piston keeps hot carbon out of the action, so the gun runs longer between cleanings and wears internals less than a direct-impingement AR. An adjustable gas regulator lets you set the action for suppressed or unsuppressed use. Bolt is a rotating bolt; feed is STANAG-compatible magazines.
11-Inch Pistol Configuration
Barrel length is 11 inches, rifled 6 lands and grooves, 1:7 right-hand twist, threaded 1/2x28. HK publishes overall length at 31.7 inches, height 7.5 inches, width 3.07 inches, and weight approximately 6.7 lb without magazine. Semi-automatic only.
Controls
HK describes the A4 as fully ambidextrous, with a slimmer profile. Trigger pull is published at approximately 4.5–5.6 lb.
HK MR556 A4 Pistol Specifications
| Manufacturer | Heckler & Koch |
| Model | MR556 A4 Pistol |
| ID Number | 81001050 |
| UPC | 642230269439 |
| Caliber | 5.56 x 45mm |
| Firearm Type | Pistol |
| Operating System | Gas operated, short-stroke piston |
| Bolt | Rotating bolt |
| Mode of Fire | Semi-automatic |
| Barrel Length | 11" |
| Barrel Thread | 1/2x28 |
| Rifling | 6 lands & grooves, 1:7 right-hand twist |
| Overall Length | 31.7" |
| Overall Height | 7.5" |
| Overall Width | 3.07" |
| Weight | Approximately 6.7 lb without magazine |
| Magazine Capacity | 30 rounds |
| Magazines Included | One 30-round |
| Feed | STANAG-compatible magazines |
| Gas System | Adjustable regulator (suppressed / unsuppressed) |
| Controls | Fully ambidextrous |
| Trigger Pull | Approximately 4.5–5.6 lb |
| Warranty | Limited Lifetime for the original retail (commercial/civilian) purchaser |
Frequently Asked Questions
Is this a pistol or a rifle?
A pistol. HK's product line for ID 81001050 is MR556 A4, 11" Pistol, 1-30RD MAG.
How many magazines are in the box?
HK lists this SKU with one 30-round magazine.
What is the gas system?
Short-stroke piston with an adjustable gas regulator for suppressed or unsuppressed shooting. The piston does not dump hot carbon into the action the way a direct-impingement AR does.
What is the twist rate?
HK publishes 6 lands and grooves, 1 in 7 inches, right-hand twist for this 11-inch 5.56 barrel.
Internal Reference:
81001050
Barcode:
642230269439
| Brand: H&K |
| Model: MR556 A4 |
| Caliber: 5.56mm |
| Capacity: 30 |
| Firearm Action: Semi-auto |
| Barrel Length: 11", 6" - 16" |
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This item cannot be shipped to the following locations due to legal or carrier restrictions:
Restriction Details
This product cannot be sold or shipped to your location due to magazine capacity restrictions. Magazine capacity cannot exceed 10rd. If you believe this to be incorrect or if you're exempt from the restriction, please contact us at 636-791-1655.
Affected States/Territories (10):
Restriction Details
Colorado prohibits magazines with a capacity exceeding 15rd. If you believe this is in error or if you are exempt from the restriction, please contact us at 636-791-1655.
Affected States/Territories (1):
Restriction Details
Vermont restricts handgun magazine capacity to 15rd. This exceeds the state's restricted capacity. If you believe this is in error or if you are exempt from the restriction, please contact us at 636-791-1655.
Vermont restricts rifle magazine capacity to 10rd. This exceeds the state's restricted capacity. If you believe this is in error or if you are exempt from the restriction, please contact us at 636-791-1655.