After 40+ years, the quest for AR-15 punch continues. Despite an ongoing effort to make it everything it’s not, the .223/5.56×45 continues to lack terminal punch on two-legged varmints. The military limits imposed by FMJ certainly don’t help, but we had a heck of a time dumping 40-pound coyotes with bullets of our choosing. Not everyone may agree that the small-bore round is primarily a varmint cartridge, however, something is driving the quest for bigger AR-15 calibers.
by Steve Markwith, contributing writer and author of Centerfire Rifles: A Buyer’s and Shooter’s Guide
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 recent 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.
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, as are AK magazines which, unfortunately, 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. The Kalashnikov round remains problematic in straight AR-15 dress due to its tapered case and diverse production, neither being 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 magazines. But for incidental use by those with large quantities of cheap 7.62×39 ammo and magazines, it may suffice. If not, two recent .30 caliber offerings of 5.56 x 45mm lineage may bridge the gap between the little .22 and full-size .30 battle rounds…
The .300 Blackout, as offered by AAC, is essentially an incarnation of the older, J.D. Jones-designed “Whisper”. You can form brass from 5.56mm/.223 cases by trimming off the shoulder area, but it’s really a necked up .221 Fireball and has 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. The case allowed use of heavy 200 grain bullets at subsonic velocity, pressure was sufficient to cycle an AR-15 and the cartridges were short enough to fit M-16 magazines.
Related: Converting a .223 to .300 Blackout
Adding a suppressor resulted in a very quiet rifle; hence the “whisper” moniker. By shifting to lighter bullets of around 110-125 grains, velocity improves to around 2300 fps. Recoil is negligible and 7.62×39 performance is achieved. Using the right bullets (like Barnes 110 or 130 grain TSX) good expansion and deep penetration are possible. Pointed bullets retain velocity for practical use out to 200 yards and any concerns about terminal effects are thus resolved. These attributes appear to be rapidly gaining favor as witnessed by the proliferation of rifles, uppers and loaded ammo from mainstream manufacturers. It was a bit surprising to see loaded ammo with UMC labels in light of the recent Remington .30 AR development. But AAC is part of The Freedom Group (as are Remington and Bushmaster). Hornady offers loads with their 110-grain polymer-tipped spitzer, plus a heavy, 208-grain subsonic bullet. Their boxes are labeled with the interchangeable “.300 Whisper” designation.
Meanwhile, Wilson Combat has begun selling complete 7.62 X 40 mm rifles, uppers and ammo. Instead of catering to heavy, sub-sonic bullets the emphasis is on the lighter .30 projectiles offered for the Blackout. The shorter bullets can use a longer case to maintain an overall length still adequate for M-16 magazine function. The longer case improves velocity, resulting in speed of 2400 fps with 110 – 125 grain spitzers. Case forming is easier, too. After knocking off .005, .223 brass can be run through a forming/resizing die. Wilson says velocity will increase after the initial fire-form, which fully expands the case. Although it won’t be as quiet as a sub-sonic Blackout/Whisper, you can still suppress the Wilson load.
Remington .30 AR
Remington’s recent .30 AR offered another step up in ballistic performance, on par with the venerable .300 Savage, itself close to a .308 Winchester. However, the case is based on a .450 Bushmaster. So, brass is an issue and loaded ammo isn’t cheap. The large case-head requires a different bolt and tweaked magazines. But, for someone with a .450 Bushmaster it might be a logical choice. In fact, a trio of .223, .30 AR and .450 BM rifles would cover just about everything. One lower receiver would accommodate all three uppers and a dedicated .22 LR unit would be icing on the cake. I was pretty excited about the .30 AR until the latest .223-based designs gained favor.
With a bucket full of cheap brass and the correct reloading equipment, a nearly indefinite supply of economical .30 AR-15 fodder is now assured. The Blackout and Wilson .30 variations share one major advantage: They require nothing more than a new barrel!
.30 Caliber AR-15 Summary
With proper head-spacing everything else is good, as is. This includes any existing magazines already on hand. The Wilson 7.62 x 40 would be my choice, based on ease of case forming. I view it strictly as a hand-loading proposition permitting use of .223 brass and .30 caliber bullets already on hand. For someone who doesn’t hand-load, or for an agency, the .300 Blackout/.300 Whisper probably makes more sense. For dispatching larger animals, these mid-sized .30s should work fairly well with careful shot placement. Add a suppressor and you’ll really have something interesting. Carried in the trunk with spare magazines and possibly two different bullet choices, just about all bases could be covered. Recoil should still be manageable, too.
The compact and familiar AR-15 if chambered in a new .30 caliber-something, may be a very useful package. Combined with the recent proliferation of suppressors, look for popularity these cartridges to rapidly grow.