8.6 Blackout promises more punch, but twist rate confusion trips up buyers

The 8.6 Blackout, created by Q Firearms founder Kevin Brittingham, is built to do what the 300 Blackout started but with more punch, and Shoot-On's Richard Mann walks through why that matters for anyone running subsonic or supersonic loads in the field.

Snapshot

Mann explains that the 8.6 Blackout uses a shortened, necked-up 6.5 Creedmoor case with the same rim diameter as the 308 Winchester, built to push heavier 0.338-caliber bullets farther and harder than the 300 Blackout. SAAMI approved the cartridge in 2026, but Mann notes the approved spec carries a 1 in 6 twist rather than the original 1 in 3 twist the round was designed around.

Key points

• Twist rate matters a lot: Mann says the cartridge was designed for an ultra-fast 1 in 3 twist to stabilize heavy subsonic bullets and boost terminal performance, but the SAAMI-approved spec uses a slower 1 in 6 twist test barrel.
• Supersonic numbers: A 185-grain bullet runs about 2200 fps from a 16-inch barrel, faster than the 338 ARC and behind the 338 Federal, according to the article.
• Subsonic advantage: Factory subsonic loads range from 285 to 352 grains, carrying notably more energy than comparable 300 Blackout or 338 ARC subsonic bullets, Mann reports.
• Bullet choice depends on twist: Mann warns against firing conventional lead-core bullets from a 1 in 3 barrel, and says 1 in 6 guns will shoot more bullet types but with reduced terminal performance.
• Hunting use: Mann says he's hunting deer this season with a Just Cause 350-grain Maker RX subsonic load out of his Q Fix, citing his own shot distances under 75 yards.

Quick take

For hunters and preppers weighing a dual-purpose cartridge, Mann's reporting suggests the 8.6 Blackout delivers real advantages over the 300 Blackout, but twist rate confusion means buyers need to match barrels and ammo carefully before trusting this round in the field.

Read the full story: shoot-on.com