I became aware of the 8.6 Blackout (BLK) through the usual internet grapevine, but not until shooting one at Faxon Firearms’ shooting lane at a SHOT Show Industry Day. At the Range, did I actually feel the need to dig deeper? This round is essentially the 6.5 Creedmoor cut back to optimize function in AR-10-style 7.62 NATO magazines and then necked up to .338 caliber. The cartridge was the brainchild of Kevin Brittingham of Q, LLC. The same guy who brought us the 300 AAC Blackout through his previous company, Advanced Armament Company (AAC).

I was able to shoot an 8.6 BLK gas gun using factory Gorilla Ammunition at that media event. Plinking steel with ease at 100, 200 and then 300 yards. What came as an absolute surprise was what a pussycat the round was to shoot. As an obsessive wild hog hunter who travels to Texas a couple of times annually to help friends with their culling efforts, the round grabbed my immediate attention.

I snagged some empty brass and a couple of loaded rounds, snapped some photos, and posted it to my Facebook page as something I thought would be interesting to wring out. Social media being what it is, most of the comments amounted to something to the effect of, “What’s the point?”

First, the 8.6 BLK is a low-pressure cartridge initially conceived for suppressed shooting using subsonic loads built from 285- to 300-grain .338-caliber bullets. These loads retain about 650-foot pounds of energy at 300 yards. Of more interest to this passionate hog hunter, deadly supersonic loads (2,300 to 2,000 fps) are also easily assembled with 160- to 225-grain bullets, which retain 700 to 1,150 foot-pounds of kinetic energy (KE) at 300 yards. By comparison, the 300 BLK retains slightly more than 300-foot pounds of KE at 300 yards (190-grain subsonic and 110-grain supersonic). The .338-cal bullets also provide more consistent ballistic profiles for greater accuracy at longer yardages.   

Converting an existing AR-10 (or short-action Remington 700 bolt rifle) to 8.6 BLK requires only a barrel change—possibly a buffer spring/weight or gas-block system change to optimize subsonic function and cycling. The cartridge was developed around a 12-inch barrel, but 8- to 16-inch barrels are available, all given an ultra-fast 1:3 rifling twist. This ultra-fast twist rate provides not only ample stabilization for heavy .338-cal bullets sent at subsonic velocities but also a more lethal terminal performance on the game due to what Brittingham calls a “blender effect.” 

I tried for a couple of years to secure a test rifle without success, eventually meeting Bruce Erlwein, a former Navy Riverine firearms instructor and someone who had developed an interest in the 8.6 BLK. He’d assembled an upper including a 16-inch Faxon barrel with Tromix muzzle brake, Jones Arms upper receiver, 15-inch handguard and bolt carrier group, and a Battle Arms Development charging handle. To get this test rolling, we finished the rifle using more generic parts, including an Anderson Manufacturing lower, ATI military lower parts, and military buffer kits. An F.A.B. Defense’s GL-CORE IMPACT recoil reduction buttstock finished it off. A Steiner T5Xi 3-15x 50mm scope was mounted in a Spuhr 34mm/0-MOA ISMS (Ideal Scope Mount System).

Gorilla Ammunition, Discreet Ballistics, Fort Scott Munitions, Steinel Ammunition Company, Mead Industries and Callaway Ballistics offer factory loads at this time. Properly head-stamped brass is offered by Alpha Munitions, Gorilla Ammunition, and Starline. Cases can also be formed from common 6.5 Creedmoor brass (Hornady brass is typically preferred due to thinner necks that require no neck turning). Dies are available from the usual suspects.

Newly released Starline brass, Lee Precision full-length dies, and Federal Champion No. 210 large rifle primers were used to assemble all loads.

My inaugural testing of the 8.6 BLK appeared in Wolfe Publishing’s Handloader No. 354, and while much was learned, the complete lack of published load resulted in an overly conservative approach. That series resulted in a plethora of solid start loads—and one push to find a true maximum with a single bullet and powder—but I ultimately ran out of time while remaining unsatisfied that I had presented a full accounting. So much so I immediately began work on this second series.      

As such, this test included bullets remaining from the original treatment; enough of Hammer Bullets’ 186- and 255-grain Shock Hammers on hand to allow ladders with two powders apiece. Enough Barnes’ 210-grain TTSX BT and 225-grain M/LE TAC-TX BT remained to assemble three powder ladders. These constituted the supersonic loads. I’d learned enough from that first test to get the most velocity possible from this round while also more thoroughly exploring some promising powder options. I then worked to adjust the subsonic loads to create true sub-1,125 fps velocities (still failing in many instances) using Hornady’s 285-grain ELD Match and 300-grain A-Tip Match bullets. These bullets produced the best subsonic accuracy in the last test. In the interests of saving time, I again didn’t crimp loads due to the deliberate firing pace. However, if I were loading for serious hog hunting involving sustained semi-auto cycling, I wouldn’t hesitate to do so.