The AR platform continues to advance on all fronts from features through new calibers. Among the latter are several intriguing .30 caliber AR-15 offerings. Driven by the quest for more powerful alternatives to the standard 5.56 NATO chambering, the .30 caliber field has evolved.
Although the 6.8 SPC shows promise, many of us can relate to something with a larger bore and few will feel under-gunned if it’s .30 caliber. This may explain the explosion of bigger cartridges capable of functioning in the smaller AR-15 platform. The surrogate 7.62s are an interesting development for .30 caliber fans, and may provide a practical alternative to the large and awkward AR-10 chambered for the standard .308/7.62×51.
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.30 Caliber AR-15 Options
A limiting factor has always been the size of the AR-15 platform which restricts the length of cartridges that can fit within its magazines. Despite some creative attempts to circumvent physics, not all .30 caliber solutions have turned out to be winners.
First up is the venerable 7.62×39. Although actually a .311 bore, it’s close enough to lump with the .308s and will approximate .30/30 performance. Ammo is cheap, but your AK magazines won’t fit an AR-15. However, they will fit the reliable Robinson Arms AR/AK hybrid design, or the MGI modular AR system with interchangeable magazine wells.
Perhaps the most interesting is Windham Weaponry’s modular AR system with interchangeable magazine wells. A few other manufacturers sell dedicated 7.62×39 ARs modified to accept AK magazines which are curved for good reasons. This whole setup throws a wrench into the AR-15 vs AK-47 debate.
The Kalashnikov round remains problematic in conventional AR-15s due to its tapered case and diverse sources; not well-suited to the dimensional parameters of Stoner’s design. A different bolt is required, meaning a completely separate upper is necessary, along with a supply of dedicated magazines. Modified AR-15 mags have appeared for use in standard lower receivers.
|7.62x39mm Upper Receivers||Optics Planet|
Palmetto State Armory
|7.62x39mm AR-15 Magazines||Brownells|
The latest Windham Weaponry “7.62×39” is one example among several others that ships with a distinctive curved 30-round AR mag. For incidental use by those with large quantities of cheap 7.62×39 ammo (buy it cheap and stack it deep) and magazines, a spare upper could be worthwhile – maybe.
But, since 2012, a better-matched .30-caliber/AR-15 combination has stolen much of the limelight. The starring .300 Blackout bridges the gap between .223 and full-size .30 battle rounds – with the added advantage of an ultra-quiet report if fired through a suppressor.
The .300 Blackout, as offered by AAC, is essentially an incarnation of the older, J.D. Jones-designed “Whisper.” This is the staple among .30 caliber AR-15 options. You can form brass from 5.56mm/.223 cases by trimming off the shoulder area, but it’s really a necked up .221 Fireball (with an alternate title of 7.62 x 35mm). The original idea, as marketed by SSK, was to offer a .30 cartridge capable of cycling through an AR-15. But not just any cartridge!
The shortened case of this one left room for longer heavy bullets weighing 200 grains or more. When fired at subsonic velocity, pressure was sufficient to cycle an AR-15 and the cartridges were still short enough to fit within M-16 magazines. The addition of a suppressor results in a very quiet rifle; hence the “whisper” moniker.
AAC embraced this concept for use by the Spec Ops community with further emphasis on fast loads. After minor tweaks they introduced the new .300 Blackout which, with lighter 110-125 grain loads, increases velocity to around 2300 fps. Recoil is negligible and performance is roughly on par with the 7.62×39 Russian.
Of interest to hunters, using the latest solid-copper 110 or 120 grain bullets from Barnes (TSX), or Hornady (GMX), good expansion and deep penetration are possible. These pointed bullets and others retain sufficient velocity for practical use out to 200 yards on average-size whitetail deer, but subsonics are another issue. Inevitably, their trajectories resemble bricks, and velocities are usually too slow for reliable expansion.
Fortunately, Hornady recently solved the expansion problem through introduction of a .300 Blackout Subsonic which incorporates their expanding 190-grain SUB-X bullet. Such projectiles require a larger chamber leade (or throat) and fast rifling twists. Normal .30-caliber twists run 1:10 to 1:12, but the slow heavyweight BLK-types need a 1:7 or 1:8 to prevent bullet yawing. These factors often limit the accuracy of lighter-weight supersonics. Five-shot groups will probably average 1.5 MOA-ish (1.5 inches at 100 yards), but that’s still plenty useful for most purposes. Read about the many .300 ammunition choices if you want more details.
As of 2020 the .300 BLK has really caught on, resulting in a proliferation of firearms, AR-15 upper-receiver assemblies, and barrels, along with ammunition from mainstream manufacturers. Most developments center on AR-15s configured as carbines or pistols, but new bolt-actions and some other types have appeared. The higher-end ammunition choices cost as much as other calibers but affordable FMJ Q-loads now exist. You can conduct your own 5.56-to-.300 conversion or buy a dedicated upper receiver outright.
|.300 Blackout Upper Receiver||Optics Planet|
Palmetto State Armory
|.300 Blackout AR-15 Magazines||Brownells|
Palmetto State Armory
Wilson Combat’s 7.62x40mm Wilson Tactical Cartridge
Not everyone is interested in .30-caliber ARs for use with suppressors. Some folks are after greater punch for use on deer or hogs. Recognizing this niche, Wilson jumped aboard the .30-caliber wagon in 2011 with complete 7.62x40mm rifles, upper receivers, and ammo. Instead of catering to quiet but loopy subsonics, the emphasis was on lighter projectiles. These shorter bullets allow use of a longer case that still fits standard M-16 magazines. The increased capacity boosts velocity to 2400 fps, using 110–125 grain spitzers.
The two drawbacks are lack of subsonic AR capability, and proprietary ammunition sourcing. But for reloaders, case forming is much easier than the Blackout. After trimming .223 brass .005”, the cases can be run through a forming/resizing die. Wilson says velocity will increase after the initial fire-form that fully expands the case. Although it won’t be nearly as quiet as a subsonic Blackout/Whisper, you can suppress this cartridge. Wilson Combat manages to cover just about all supersonic bases through a selection of effective loads which were obviously developed from firsthand experience.
Remington .30 AR-15 – FAILED
When introduced in 2008, this cartridge offered great promise. It provided another clear step up in .30-caliber AR-15 performance, on par with the venerable .300 Savage (itself close to a .308 Winchester). However, the fat case with its rebated rim still required a different bolt and tweaked magazines. I was pretty excited about the .30 AR until the .223-based designs gained traction. Possibly for these reasons, the .30 AR was nearly DOA upon arrival. As of 2020, it’s deceased. Even Remington no longer offers ammunition.
Wilson Combat .300 HAM’R
This one’s fairly new. It’s also the culmination of an all-out effort to achieve maximum .30-caliber velocity in the AR-15. The parent case is, again, the 5.56×45 NATO (or .223), stretched beyond their 7.62×40 WT. This translates to a gain of 0.260” (more than a quarter-inch) over the .300 BLK, resulting in a significant boost in velocity. The HAM’R really begins to shine as bullet weights increase. Comparing 125-grain types, the increase can be 300 fps over a .300 BLK – resulting in a stunning muzzle velocity of 2,500 fps!
The leade is also optimized for shorter supersonic loads, and the barrel incorporates a slower 1:15 rifling twist. Freed of the dimensional concessions required to accommodate ultra-heavy subsonic projectiles, much better accuracy is attainable; on the order of 1 MOA.
The downsides? Exclusion of some excellent longer bullets (including many monolithic types), and the need for proprietary ammunition.
.30 Caliber AR Effectiveness
As for hunting, for .30 caliber AR-15 options, my personal experience is limited to the .300 Blackout. But since it’s the lowest rung of the .30-calber ladder, the results should have some relevance. The following is a sampler based on firsthand action.
Our whitetails run fairly large but, so far so good with the .300 BLK, using solid-copper Barnes TAC-TX in 110 or 120-grain weights (the latter as a factory offering). These TSX derivatives expand reliably and retain nearly all of their weight. As such, they behave like heavier bullets. All of our deer were one-shot pass-throughs but, judging by the results, they performed similarly to a few larger-caliber TSX specimens we’ve managed to recover – all of which displayed picture-perfect performance. Having witnessed ballistic testing of Hornady’s similar 110 GMX .300 BLK, I’m betting it’ll work equally well. The MV of these 110s will run around 2350 fps from a 16-inch carbine.
Coyotes, Bobcats, Etc.
Our Northern New England coyotes have wolf genes. Some can top 50 pounds, but they’re no match for Hornady 110 V-Max. There are many high-quality .223 rounds for an AR-15. My handloads are the equivalent of Hornady’s factory offering, with a chronographed MV of 2350 fps. The 100-yard POI is usually similar to 110 Barnes TAC-TX. If zeroed around 1 ¾ inches high at that range, they’ll strike that amount low at 200 yards. Accuracy is at least as good as anything else I’ve seen in this caliber.
Using a suppressor, I’ve taken a bunch of coyotes and bobcats with Hornady’s Subsonic 190-grain SUB-X load. Like other subsonics, this one is a short-range affair best used (for these purposes) inside 125 yards. Because MV is only 1050 fps, if zeroed with the above 2350 fps loads at 100 yards, POI will shift downward around a foot! But, SUB-X certainly is quiet when suppressed!
FYI, Sig has a similar load in the works. For what it’s worth, you can also fire supersonics through a suppressor. They’ll be quieter, but their telltale sonic cracks will be obvious. To me, supersonic .300 BLK loads sound a lot like snappy .22 LR high-speed rounds that were fired through bare rifle barrels. Regarding self-defense, I’d go with the latter two loads – especially if indoors.
There are no feral hogs in my area, but Wilson Combat has plenty of experience with these tough critters as well as deer, etc. Their website is thus a goldmine for good bullets, as well as their proprietary cartridge details. Interestingly, as of December 2020, the .300 Blackout is still listed as Wilson’s best seller. Part of the reason no doubt involves availability of affordable FMJ Q-loads, suitable for practice or plinking. Another driving force is the popularity of suppressors which require subsonic loads for true effectiveness.
The .300 Blackout and Wilson .30 variations share one major advantage: They require nothing more than a new barrel! With proper head-spacing everything else should be good to go. For the most part, this also includes magazines. I use 10-round P-mags as-is with my .300 BLK ARs, but if using hi-cap types, their internal vertical ribs can squeeze larger stacks of stubby rounds inward through bullet contact. Some users file down their polymer ribs while others switch to newer .300 types. Caution: Owners of 5.56/.223 ARs should avoid caliber mix-ups by using distinctive mags! Consider a labeled dust-cover, too.
Suppressed Users or Non-Reloaders
For someone who doesn’t handload, the .300 Blackout makes the most sense. Add a suppressor and you’ll really have something interesting. Stashed in an assault-type case (with designated magazines), just about all bases could be covered. To take full advantage of such a system, you’ll need an optic with trajectory-compensating features capable of accommodating disparate POIs.
For Reloaders? With a bucket full of 5.56 brass and the correct reloading equipment, a nearly indefinite supply of economical .30 caliber AR-15 options would be assured for any of the above calibers. Assuming suppressors are off the table, especially if maximum performance is the goal, the Wilson .30s have potential based on ease of case forming. I view them more as hand-loading propositions which can take advantage of .223 brass and .30 caliber bullets already on hand.
Final .30 Caliber AR-15 Thoughts
Worried about availability of .30-caliber loads? Well, the .300 BLK has really grown legs. No, it’s not as widely circulated as 5.56 NATO, but the BLK has certainly gone mainstream. The Wilson loads are niche calibers which, for many AR owners, might not be a big deal.
Here’s another option: Pop the two pins on your lower receiver and drop in another pre-zeroed upper receiver assembly! Viola, you now have an instant transformer capable of handing 5.56 or the above .30s (along with a number of other spiffy new AR-15 calibers).
The .30 caliber AR-15 options may look out of place in the deer woods, especially when compared to Dad’s Remington M-742 .30/06, but it’ll kick a lot less and stay on target better thanks to the AR’s straight-line design. As a further bonus, especially for younger or smaller shooters, less recoil is good. All of the AR-based .30s are downright mild and less concussive. Their adjustable stocks are the icing on the cake.
Of course, there are other new intriguing calibers that seemingly appeared out of nowhere. At the moment I’m trying to resist a .350 Legend barrel – but that’s another story.