Trials and Tribulations of the 7.62x39mm AR

There was a time when I really got into guns, and I wanted an AR in 7.62x39mm. Why? I purchased two thousand rounds of 7.62×39 and was bored of shooting them out of an AK. Why not get a new platform that could fire the same round?

Being broke at the time, I researched everything. There was no such thing as an impulse purchase for me! The more I researched, the less I wanted an AR in 7.62x39mm.

But, before we cover the trials and tribulations of the 7.62x39mm AR, let’s examine why one may want such a rifle or AR pistol. 

Why an AR in 7.62×39?

I originally wanted one because I had a ton of ammo, and the ammo was a bit cheaper than 5.56/.223 Remington. Thanks to the rising cost of ammo and dwindling supply, that’s not really the case anymore. The 7.62×39 offers a fairly significant increase in short-range power compared to the 5.56, as it’s bigger, penetrates deeper, and typically hits harder. This makes it a great hunting round within 300 yards. In an AR, the round tends to be more accurate due to the fact the AR is more accurate than the AK. 

On top of being more accurate, it’s easier to accessorize an AR than an AK. This includes adding optics. Not just optics, though; adding lights, bipods, and the like is much simpler. Plus, the AK’s ergonomics are that of a WW2 submachine gun. They are workable but impress no one. ARs have superior ergonomics with better controls all around. 

AR in 7.62
The AR has better ergonomics for the AK round, but is it worth the hassle?

The 7.62x39mm round also works well from a short barrel. In an AR pistol or SBR, you get a great round that doesn’t suffer much from shorter barrels. The 7.62×39 often becomes a bit like a poor man’s .300 Blackout without the subsonic loadings being common. 

It takes all the perceived benefits of the AR and gives you the ability to fire the standard AK round. These guns use standard AR multi-cal lowers. This can make it as easy as swapping an upper from your 5.56 rifle…right?

Well, maybe not. There are several problems with the AR in 7.62x39mm, and it might be best to stick with an AK or some of the more interesting rifle selections. 

AR15 in 7.62
The 7.62×39 is a powerful round that just barely fits in the AR platform.

The Trials and Tribulations of the AR in 7.62×39 

The AR in 7.62x39mm has four main problems. Its modularity makes it possible to mitigate some of these issues. We’ll discuss these issues and dive into what you can do if you choose to use the AR chambered in an AK caliber. 

Feeding and Magazines 

First off, the magazines look goofy as hell. Seriously, looking good is half the battle, and these mags will not max out your ‘riz if you know what I’m saying. In reality, it’s the taper of the AK round that requires the curve in the AK’s magazine, and the standard AR mag doesn’t have that kind of curve; in fact, the mag well doesn’t really allow it. Luckily, some companies have produced magazines that fit inside the gun and have their own weird curved design. 

7.62x39 AR magazine
The magazines are a serious weak point.

The problem isn’t necessarily just looks. In fact, the weird design creates some serious issues with feeding. The massive curve in the magazines makes their design tricky. Sometimes, this results in feeding issues, which are most often caused by the forward lip of the magazine. They just aren’t cut low enough sometimes, which means they catch and fail to feed. 

The solution comes from having to find reliable and capable magazines. The one most commonly cited by AR enthusiasts is Duramag, which seems to be the most reliable mass-produced option for use with a standard 5.56 lower. 

Deep Seated Primers 

There are quite a few different brands and countries of origin for 7.62x39mm ammunition. It turns out that when the Soviet Union gives AKs away, you get tons of countries producing tons of ammo for the platform. In these countries, a specification doesn’t seem to be something followed closely but a loose set of suggestions. This includes primer depth. 

With Western ammo, you know the primer is one set depth, and your standard AR firing pin will strike it and ignite without an issue. With AK ammo, the primer might be too deep for your firing pin. Your firing pin might hit the primer but fail to ignite it. This obviously creates reliability issues. 

AR 15 front view
The AR is a natural multi-cal option.

This means you might need an extended firing pin, which exists for the AR; it’s specifically designed for this kind of situation. A longer firing pin can help deal with the depth issue, but not always. Some dedicated shooters will even dremel and shorten the collar around the end of the firing pen. This allows the pen to extend even further, but it’s not something I suggest. I tend to be more cautious with making any firearm modifications with a Dremel. 

Hard Primers 

One common trope between all these ammo manufacturers seems to be a reliance on hard primers. Hard primers are harder to ignite and take a real slap from the firing pin to successfully ignite. With that in mind, most standard AR trigger springs don’t have the oomph to always reliably ignite the hard primers of the old Soviet cartridge. 

.30 cal in AR mag
The little .30 cal looks big in the AR magazine.

This results in “clicks” instead of “bangs,” and isn’t always a consistent problem. However, one failure per mag is pretty annoying and not reliable for much beyond plinking. The cure to hard primers is the Wolff extra power AR hammer spring. This creates a heavier trigger and limits your ability to use aftermarket trigger options. 

Bolt Lifespan 

The 5.56 has a nice strong bolt with a bolt face and lugs. It’ll last for tens of thousands of rounds if built correctly. What happens when you shove a 7.62x39mm bolt into a 5.56 platform? You get a thin, flimsy design. It is flimsy enough to fall apart in just a few thousand rounds. If that happens, you don’t even have a single-shot rifle; it’s just an abject failure all around. It’s tough to cure this problem. 

AR bolts
Notice how thin the 7.62×39 bolt face is.

The only thing you can do is try and find high-quality bolts that can withstand abuse. They need to be high-pressure tested and magnetic particle-inspected at the very least. There is no perfect cure for this problem, but that’s the closest option we have. 

The Better Alternatives

The AR series is a great platform, but there are options outside of the traditional AR lower that still give you most of the AR advantages. They make some compromises but are ultimately the better option. The downsides include the lack of bolt hold open and some non-AR-like controls. However, we still get better than the AK controls and a more accurate and customizable gun. 

The CMMG Mk47 

The CMMG Mk47 isn’t quite the same size as an AR-15, but it’s not much larger. The bigger size and proprietary design ensure you don’t have some dinky little bolt. It’s built for the 7.62×39 round. You also get to use AK mags, which is a better option for the old Soviet 7.62×39. 

The TEC 47 

Much like the Mk47, you have an AR platform that uses AK magazines. Unlike the Mk47, the TEC 47 utilizes an AR-10 platform. It’s a standard-size AR-10 that just happens to fire 7.62×39. This makes some part’s commonality a bit easier. It increases weight, but not by much. It’s super low recoiling and a very nice rifle. 

The AR and the AK 

Blending the AR and AK is difficult. The AR is really best left for rounds designed for it. I hate to suggest a 7.62x39mm AR to anyone outside of the MK47 and the TEC 47. However, if you are going that route, hopefully, you will understand the problems you might face and how you can succeed a little better with the platform. 

Travis Pike is a former Marine Machine Gunner and a lifelong firearms enthusiast. Now that his days of working a 240B like Charlie Parker on the sax are over he's a regular guy who likes to shoot, write, and find ways to combine the two. He holds an NRA certification as a Basic Pistol Instructor and is probably most likely the world's Okayest firearm instructor. He is a simplicisist when it comes to talking about himself in the 3rd person and a self-professed tactical hipster. Hit him up on Instagram, @travis.l.pike, with story ideas.

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