8.6 Blackout clears SAAMI, but twist rate debate lingers

The 8.6 Blackout, developed by Kevin Brittingham's Q LLC, is a short-action cartridge built on a shortened, necked-up 6.5 Creedmoor case that shares the .308 Winchester's rim diameter, and it just cleared SAAMI approval in 2026.

Snapshot

Writing for Shoot On, Richard Mann explains that the 8.6 Blackout was engineered to beat the .300 Blackout's terminal performance and reach at both subsonic and supersonic velocities using 0.338-caliber bullets. The cartridge's ideal 1:3 twist rate complicates its SAAMI standardization, since the approved spec uses a slower 1:6 test barrel instead.

Key points

• Case design: The 8.6 Blackout is built from a shortened, necked-up 6.5 Creedmoor case, loaded to a max average pressure of 62,000 psi with a 0.473-inch rim diameter matching the .308 Winchester.
• Supersonic punch: Mann reports 185-grain supersonic loads reach about 2,200 fps from a 16-inch barrel, with muzzle energies of 1,800 to 2,000 foot-pounds, outperforming both .300 Blackout and 338 ARC.
• Twist rate complication: Q engineer Nick Schafer tells Mann that SAAMI testing used a 1:6 twist barrel for broad bullet compatibility, while the cartridge's ideal 1:3 twist drives much higher bullet RPMs for better subsonic expansion.
• Heavy subsonic bullets: Factory subsonic loads run from 285 to 352 grains, giving the 8.6 Blackout a notable energy advantage over comparable .300 Blackout and 338 ARC subsonic offerings.
• Industry momentum: Wilson Combat is adding a NULA Model 20 in 8.6 Blackout with a 1:6 twist, and Mann notes more rifles and ammunition are reportedly in development.

Quick take

Mann, who has tested the cartridge for roughly two years and plans to hunt with it this season, argues shooters chasing the cartridge's full super/subsonic potential should seek out a 1:3 twist rifle, with Q currently the best source for one.

Read the full story: shoot-on.com