HK MR556A1 5.56 NATO
Model: 81000579
HK MR556A1 5.56 NATO
Model: 81000579
Full Specifications
Threaded 1/2x28 barrel: compare 5.56 / .223 suppressor prices.
About This Firearm
The HK MR556A1 is a short-stroke piston semi-automatic rifle in 5.56 NATO built for range and defensive use. It has an MSRP of $3,499. Its gas system is closed, so exhaust gas never enters the receiver, which HK says keeps the rifle running cooler and cleaner, with the gap widening in dust, sand and mud.
It is sold optics ready with one magazine and no sights. The upper is a flat-top with a MIL-STD-1913 rail machined into it, ahead of a rifle-length M-LOK handguard, and a two-stage trigger comes fitted, so neither the rail nor the trigger needs changing. The stock adjusts through six positions over 96 mm of travel. The muzzle carries the bird cage flash hider HK calls the Compensator, and the thread beneath it is unmarked, so a suppressor mount means measuring it.
If you're cross-shopping, a Daniel Defense DDM4 V7 Pro has an MSRP of $2,470 and uses direct impingement behind an 18-inch barrel. A Sig Sauer MCX Spear LT has an MSRP of $2,619.99, is also piston driven and folds to 34.3 inches. Both weigh 7.40 lbs, so the HK carries 1.20 lbs more before an optic and a loaded magazine go on, and that weight sits in the piston and the heavier barrel.
Best For
Strengths & Limitations
- The 16.5-inch barrel is a medium contour, which puts more steel around the bore than a lightweight profile carries.
- The receiver rail is machined into the upper as one piece, so there is no barrel-nut joint between the optic and the handguard.
- HK assembles the rifle in the USA using US and German-made components.
- Sights are sold separately now, where HK's earlier version of this rifle came with Troy Industries micro sights, a 30-round steel magazine, a multi-tool, a lock and a case.
- The handguard is rifle-length and HK's own, so an owner who wants a shorter forend buys an HK part or nothing.
- Spares for the barrel, piston and carrier come from HK, so a wait is part of owning one.
Category Rankings
How the HK MR556A1 5.56 NATO ranks among full-size 5.56 NATO rifles.
Compatible Ammunition
Find the best prices on compatible 5.56 NATO ammunition.
Shop 5.56 NATO Ammo →Ballistics Calculator
Calculate trajectory, drop, and energy for 5.56 NATO ammunition.
5.56 NATO Ballistics →Alternatives to Consider
Similar full-size 5.56 NATO rifles ranked by similarity.
| NAME | BEST PRICE |
|---|---|
|
Daniel Defense DDM4 V7 Pro 5.56 NATO
Daniel Defense
|
— |
|
CZ Bren 2 Ms Carbine 5.56 NATO
CZ
|
$2,403.99 |
|
Anderson AM-15 5.56 NATO
Anderson
|
— |
|
FN 15 TAC3 5.56 NATO
FN America
|
$1,699.99 |
|
Palmetto State Armory PA-15 5.56 NATO
Palmetto State Armory
|
— |
Frequently Asked Questions
Is this the same thing as an HK416?
It is the semi-automatic version of it. HK calls the MR556A1 a direct descendant of the HK416 that uses many of the same parts and assemblies.
Will AR-15 parts fit it?
Not the important ones. The barrel, piston assembly, bolt carrier and handguard are HK designs with no mil-spec equivalent. The grip, stock and magazines are the parts that cross over.
Does it need a tax stamp?
No. The barrel is 16.5 inches, clear of the 16-inch minimum for a rifle.
