Why The 7.62×39 AR-15 Makes a Great, Accurate, Reliable General Purpose Carbine

Like many former “ground-pounders”, my view of the AK family of firearms used to be pretty stereotypical: They go “bang” when you pull the trigger and throw rounds in the general direction you point them towards. I used a bunch of AK variants during my Army career but I never gave Mikhail Kalashnikov’s simple masterpiece much thought beyond its “minute of man” accuracy, cheek-eating folding stock and hefty muzzle flash. Taking the time to actually zero them can make AKs aim-worthy but they are still not known for precision. I just assumed the 7.62x39mm cartridge they fire was likewise incapable of doing much more than moving through the air and hurting whatever it occasionally hit. Several years ago I learned that I was very, very wrong.

Not long after retiring from the Army I decided to stop lugging my .308 Win.-chambered AR around the woods during deer season. Don’t get me wrong—I love me some .308 Win. I either had an SR25, M1A or a G3 rifle variant in my hands for the last 12 years of my career. But once I hung up my fightin’ boots for good, the willpower required to punish myself with more weight and bulk than necessary evaporated. I resolved to build a carbine on the smaller AR-15 sized platform but chambered for a cartridge suitable for whitetail, hogs, coyote and home-defense. At that time my practical choices were limited to 6.5 Grendel, 6.8 SPC, .300 Whisper, and 7.62x39mm. I liked the .300 Whisper in both sub and supersonic loadings but I wanted a cartridge with lots of factory ammo options and .300 Blackout had not yet made its SAAMI debut. Previous bad experiences with 6.8 SPC ruled that one out for me. Parts to build 6.5 Grendels were non-existent at the time and again, no factory loads were offered. That left me with a Russian dance partner named 7.62×39. I figured that if it would at least shoot as well or better than a .30-30 Winchester at 100 yards, the end result would be a suitable woodlands deer gun.

Imagine my surprise when right out of the gate the first one I built shot consistently below 1 MOA at 100 yards—with multiple factory loads.

Constructing what has become my general-purpose carbine was not without some hiccups. For some reason I never slow down enough to do much research, so I dove in without any idea of others’ lessons learned. I picked what I thought looked like the best components from a very limited field of choices. I quickly learned that firing pins need a slightly longer protrusion through the bolt face and/or a wider tip in order to reliably ignite most of the eastern European, steel-cased ammunition primers. A simple web search would have told me that ahead of time. I also found that most 7.62×39 AR barrel makers do not have a good grasp of gas ports. It took a lot of trial and error to find the right port sizes and adjustable gas block or buffer/action spring combinations for different length gas systems. As more barrel makers have come on line, factory port sizes are not as far off as they once were. But I still typically have to open them up to differing degrees, dependent on the gun’s setup.

The 7.62×39 AR configuration uses the same bolt carrier as 5.56 variants but a different bolt, firing pin, extractor and magazine are required for its different cartridge design and dimensions. I used to consider this a detractor when compared to chamberings that use the same bolt carrier group and mags. But after a former customer managed to destroy his custom 5.56 AR by hammering his bolt closed on a .300 Blackout and then firing it, the different bolt and magazine requirement doesn’t seem like such a bad thing after all. Ammunition cost and availability are huge advantages in 7.62×39. In past years when other cartridges were scarce and prices are inflated, this ammo was easy to find and prices held steady thanks in large part to supplies coming from Europe.

Several factory loads are available from US and foreign factories that bring accuracy and downrange performance to the party in one package.

My favorite factory fodder is Federal’s 123 gr soft point, which also happens to be a very good expander in tissue. Their 123 gr Fusion load is also very good at keeping rounds together on target and doing heavy tissue damage. Hornady’s 123 gr SST and SST-Black loads also shoot nice groups and expand well in critters. The first season that I hunted with my 7.62×39, I took a 125 pound buck at 120 yards. The Hornady 123 gr SST projectile did exactly what it was designed to do with a clean, one-shot drop.

Decent ammo choices from across the pond include both Tul and Wolf hollow points. Two of my customers use Russian hollow points for permitted culling and livestock predator control with great success. A whole host of factory loads are available from other manufacturers too, mostly in FMJ and soft point designs. The only factory round I cannot get to run reliably in any AR is Golden Tiger’s 123 gr FMJ. That is a real shame because this ammo’s boat-tail projectiles are very accurate (most other 7.62×39 FMJs are shorter Spitzers). Primer sensitivity with this stuff is too sporadic from one box to another to be relied on for anything outside of target shooting in an AR. I have trouble with it in SKS rifles too. Beyond that, the other brass and steel-cased loads work well in ARs. Every so often I get a tough Russian primer but it does not tend to be a regular problem. As with any caliber, be sure that if you shoot heavily lacquered steel cases, you pay special attention to keeping your chamber clean during maintenance to avoid any long term buildup or stickiness.

So what’s not to like about a 7.62x39mm AR?

Nowadays my simple answer is “nothing”. But several obstacles existed back when I started building in this caliber. For starters, very few sources for quality barrels could be found. Magazines were crummy at best and all had to be modified to work well. Today many barrel manufacturers offer some form 7.62×39 options starting around 8 inches and growing from there. In fact, surprisingly good shooting barrels can be had for around $100. I use a brand at that price point and for the money; I get smooth, nitrided 16” barrels that shoot sub-MOA with factory ammo.

Magazines used to be the biggest Achilles Heel of this AR configuration.

For several years there simply were not any good options in AR-style mags. Today a handful of companies produce mags in various capacities. I have found that the steel-bodied, 10-round mags from C-Products (CPD) and AR-Stoner (ARS) to be relatively problem free but the 30-rounders are a different story. The older models that are long like an AK mag usually need to be modified to work well. Fortunately CPD came out with a better 7.62×39 mag style for AR lowers a few years ago. These are available in 20 and 28 round capacities, have a Teflon-type coating inside and out and work very well without being modified or de-gunked right out of the package. AR-style 7.62×39 mags trip the bolt stop on empty magazines and function normally with the manual bolt lock.

Several current manufacturers have tackled the mag problem in an entirely different manner, designing their ARs to accept AK magazines. I have tested several off-the-shelf guns for Shooting Illustrated magazine over the years. One thing that has been consistent with them all is that they are very choosy with regard to which magazines fit. I have a mixture of steel AK mags, some from stateside vendors and some that have come back from overseas battlefields. Each gun type would accept some and not others due to the wide variation in AK magazine dimensions. Modern polymer mags worked the best in the AR/AK hybrids I tested. These magazines typically rock into position just like they do in AK firearms. Paddle-style mag releases are also common. The main downside to the AR/AK setup is that the bolt cannot be locked to the rear when using AK mags. That is not a problem if your manual-of-arms familiarity is exclusive to the AK or roller-locked HK firearm families. But for traditional US-made semi-auto shooters, there is a learning curve associated with non-locking magazines. Regardless of whether a 7.62×39 AR uses AK or AR-pattern magazines, the very long 30-round models are difficult to rest on the ground when prone and require a tall bipod or stack of sandbags when shooting for precision.

Handloading the 7.62x39mm cartridge for ARs is easy and produces excellent ammunition.

Barrels range from 1:8 to 1:10 twists, which mesh well with the 122 to 154 grain projectiles that are most commonly found in factory ammo. Engle Ballistic Research loads 220 grain subsonic soft point and open tip expanding loads that stabilize reasonably well, even in 1:10 twist barrels. While there is some wobble in the looser twists, groups are still typically in the 1 to 1.5 MOA range at 100 yards. Detroit Ammunition’s 150 gr subsonic soft point load is also available for the quiet crowd, but accuracy is not all that good in my experience. A much wider variety of weights and designs is available to the roll-your-own crowd. Steel cases cannot be reloaded and some brass cases are Berdan primed, so check before you buy a case of them. Most of the US ammo uses Boxer priming in both large and small rifle primer sizes and brass from companies like Winchester and Lapua is also available. A large variety of 123 grain FMJ, SP and ballistic tipped projectiles are offered by several bullet makers. The .310 diameter projectiles perform best out of like-sized bores but dies are available that allow loading .308 projectiles in 7.62×39 brass. Some folks have reported decent accuracy with .308 bullets but I have not tested them in my guns. That would certainly open up a much wider variety of projectile weights and designs.

At first I stuck to building 7.62×39 ARs with 16 inch barrels. I’ve since built many as pistols and SBRs in 9” and 11” lengths. I’ve built a few 14.5” guns but for some reason they are harder to get decent accuracy from in this chambering. Performance with chrome moly/chrome lined, stainless steel and CM/nitrided barrels in both light and medium contours has been excellent in 16” carbines out to at least 300 yards. Several of my customers shoot their 16” guns at 500 to 600 yards. But just as with 5.56 NATO, any amount of crosswind really pushes the projectiles around once you get past o the 300 yard mark. The shorter barrel guns are also fantastic shooters. I have no trouble getting sub-MOA accuracy out of them and function is excellent with all lengths, so long as the gas system is set up correctly. I use adjustable gas blocks on nearly everything I build in this chambering, especially if it will be suppressed.

The 7.62×39 cartridge is a good solution for gaining a bit more payload without simultaneously increasing the AR’s size.

Looking back to my soldiering days, I’m glad I was unaware of this cartridge’s accuracy potential while I was on its receiving end. I distinctly remember thinking—while watching incoming rounds impact walls and dirt or snap through the air near me—that the odds of being hit from beyond 100 meters were pretty slim. It’s a good thing the bad guys were using inaccurate, un-zeroed guns that were usually pointed and not aimed. Otherwise I might have had a healthier respect for—and fear of—this stubby little performer.