TFB Review: Heckler & Koch MR556 A4 Rifle

In the world of AR15s, the sky truly is the limit with almost endless options for every budget. As of the time of this writing, there are complete rifles available online starting at $349.99. With such a wide variety of pricing, looking at some of the most expensive options can seem wild. I never understood why the HK line of rifles was drastically more expensive than other options on the market. I decided to take the plunge and purchase one so we can find out what the buzz is all about with this German tank of a rifle. Let's take a closer look at the Heckler & Koch MR556 A4 rifle.

Specs

So when we look at the spec sheet of the MR556 A4, it starts to look different compared to other offerings on the market. The MR556 A4 is the closest thing civilians can get to owning a true 416 variant rifle from HK. Having the legendary short stroke piston system allows for the carbon fouling to be regulated out front, keeping the action clean with less debris entering from firing the rifle. Add in full ambidextrous controls, an angled magwell flare and a match-grade cold hammer forged barrel and you have a really capable rifle. For most rifles in the market, you can either go with a match-grade rifle or a rifle that will run until the end of time. Typically, you have to choose one option or another, but the MR556 A4 is one of those rifles that delivers both. Most users report having sub-MOA accuracy with a cold hammer forged barrel, which is impressive to say the least, but I will touch on that more later in this article.

When it comes to the trigger, my example has a trigger weight of 4.75 lbs with a defined wall, crisp break and defined audible reset. Every MR556 A4 comes with a two-position gas block that comes straight off the 416 line of rifles, allowing you to adjust the system depending on whether you want to run your rifle suppressed or unsuppressed. Other small things I like are the HK's own pistol grip and adjustable stock, as well as ambidextrous controls, including a right-side bolt release that also allows you to lock the bolt to the rear. My MR556 A4 came with a soft side case as well as an HK-branded tool kit. MSRP on this rifle is $3,999.99 and it is available as the 16.5” rifle or 11” pistol variant.

Range Time

Over the last four months, I have roughly 825 rounds through the HK MR556 A4 over a half dozen range sessions. For this rifle, I decided to install an EoTech EXPS3 DCA optic with a 3x magnifier, Steiner DBAL and a Ground Combat Solutions Modular Vertical Grip. AR15s usually all feel the same when it comes to the overall controls or ergonomics, but the MR556 A4 does seem different to me. Things that can sometimes annoy me, like the magazine release and safety selector, are easy to access and feel perfectly proportioned.

Accuracy and Reliability

I tested the MR556 A4 with PMC XTac 55gr, as well as SIG Sauer Match 77gr ammo. I did a group of 5 shots from the bench with roughly 8-10 seconds between each shot. For both ammo types, I shot three groups of 5 rounds to make sure I could get the best groups possible. At 100 yards, the 55gr XTac shot an average group of 1.44” with the best group being 1.35” out of the 3 groups. With the SIG Sauer 77gr Match ammo, the best group was .72” with the average group being .86”, making it incredibly accurate for a 16” AR15. I’ve always been happy with how the SIG match ammo runs out of gas guns, but this one surprised me at just how well this rifle performed.

When it comes to reliability, this is where this rifle truly shines. The MR556 and 416 piston system is widely regarded to be the toughest weapon system developed for the AR15. Every aspect of the barrel design, piston system and overall quality is built to last even if you take this rifle to hell and back. Everyone likes to complain about the price, but there's a reason why these guns cost significantly more than most higher-tiered rifles. Heckler & Koch wanted to make the toughest rifle possible over everything else. As a result, it's expensive, but the reliability of this rifle is one of the best on the market and I would put it against anything when it comes to longevity.

Place In The AR Market

The AR market is a really busy space where you can find a rifle at any price point, but this HK MR556 A4 is one of the most expensive on the market. I said it earlier, but this rifle was built for reliability as well as being an extremely accurate firearm. There are some people who want the absolute best right out of the box from the factory. They often don't care about price or what it takes to get the best of the best. So there are certainly people out there who want to own this rifle because it's a modern-day legend of reliability and even though it's incredibly expensive, it's hard to see an alternative when it comes to a hell and back rifle. If I had to pick one rifle to last me the rest of my life, no matter what happens, I would choose this MR556 A4 and that's as high of praise as this rifle can get.

Overall Thoughts

So the big question that I know everyone is asking is whether or not this HK MR556 A4 is worth the $4,000 price tag. You can certainly get a mid-range rifle and have enough left over to get a great optic, as well as any accessories you may want. For the vast majority of people, this will be the route you go. For those of you who want the absolute best in terms of accuracy and reliability, there's no real substitution and the MR556 A4 is one of those rifles that you can buy and have a rifle that will last your lifetime and will perform when you need it most. I think it's a really special rifle, and even though it's crazy expensive for an AR15, I would still think the price of admission is certainly worth what you get.

Let me know your thoughts on the MR556 A4 down in the comments below. If you have questions on the MR556 or firearms in general, feel free to shoot me a message on Instagram  @fridgeoperator. Stay safe out there and we will see you in the next review.

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