You’re tucked into a mesquite thicket at first light, rifle shouldered, waiting for that boar to slip through at 75 yards. Do you send a 200-grain .300 Blackout subsonic for a whisper quiet kill, or let loose an 8.6 Blackout brute built to hit like a sledgehammer?

Both cartridges dominate the suppressed, short-barreled world—but they aren’t built for the same job. One is a decade-proven AR-15 favorite; the other is a Creedmoor-born wrecking ball shaking up the AR-10 space. This guide breaks down real ballistic differences, recoil, hunting performance, home-defense considerations, cost, and practical field behavior—so you pick the right tool for your mission.

What Is .300 Blackout?   

Launched in 2011, .300 Blackout was designed to give the AR-15 reliable cycling, full power, and clean suppression using both subsonic and supersonic loads. It excels in 5–10" barrels and remains one of the most versatile short-range hunting and defensive cartridges on the market.

What Is 8.6 Blackout?   

Released in 2022 by Q (with barrel support from Faxon), 8.6 Blackout is essentially a .338-caliber powerhouse derived from the 6.5 Creedmoor case. It’s optimized for the AR-10 platform and tuned for 12" barrels, heavy subsonic bullets, and extreme quiet suppressed performance—with far more mass and energy than .300 BLK.

8.6 Blackout vs .300 Blackout: Quick

Comparison

(Load-dependent values; representative factory data.)

Category	8.6 Blackout	.300 Blackout	Edge
Recoil	9–12 ft-lbs (heavier AR-10)	5–8 ft-lbs (AR-15)	.300 BLK
Subsonic Effective Range	~200–300 yards	~150–250 yards	8.6 BLK
Subsonic Energy	~500–700 ft-lbs	~400–550 ft-lbs	8.6 BLK
Bullet Weights	210–360 gr	110–240 gr	—
Wind Resistance	Higher BC bullets	Moderate BC	8.6 BLK
Hunting Application	Deer, hogs, black bear	Hogs, predators	8.6 BLK
Home-Defense	Deep penetration	Controlled penetration	.300 BLK
Ammo Price	$1.50–$2.50+	$0.80–$1.50	.300 BLK
Platform	AR-10, Bolt Action Rifles	AR-15, Bolt Action Rifles	.300 BLK

Recoil & Shootability   

Recoil determines how fast you can make follow-up shots—especially in short barrels and braced pistols.

.300 Blackout Recoil   

•Subsonic 200–220 gr loads produce 5–7 ft-lbs in a typical AR-15.

•Light, smooth, and extremely manageable with a suppressor. 

Why it matters: It’s easy to stay on target inside 150 yards and maintain your zero without fighting the gun. 

8.6 Blackout Recoil   

•Heavy 300–350 gr subsonics generate roughly 9–12 ft-lbs in an AR-10.

•Feels similar to a light .30-30 carbine—authoritative but not punishing. 

Takeaway: More recoil is the tradeoff for significantly more mass and downrange energy.

Trajectory & Effective Range   

Neither cartridge is a long-range sniper round in subsonic form—but trajectory still matters in the brush.   

8.6 Blackout   

•300–350 gr subs at ~1,000–1,050 FPS

•Expect ~25–30 inches of drop at 200 yards with a 100-yard zero

•Higher BC bullets buck wind more effectively 

.300 Blackout  

•190–220 gr subs at ~1,000–1,050 FPS

•Similar drop curve, slightly more wind drift

•Supersonic 110–150 gr loads can stretch to 300 yards for hunting 

Verdict:   

Inside 200 yards, both are predictable. Past that, 8.6 BLK holds onto stability and mass

better.

Terminal Performance: What Happens on   

Impact   

This is where the gap becomes unmistakable. 

8.6 Blackout   

Subsonic .338 projectiles simply hit harder.

•300–350 gr bullets maintain 500–700 ft-lbs at 100 yards (load dependent)

•Large wound channels, deep penetration

•Great for medium-to-large game, especially with expanding subsonic bullets

•Excellent shoulder-breaking capability on larger game

.300 Blackout   

Still extremely effective at the right range.

•190–220 gr subs generate ~400–550 ft-lbs at muzzle 

•Ideal for hogs and predators

•Better controlled penetration in defensive settings 

Verdict:   

•Hunting: 8.6 BLK dominates for deer, hogs, black bear, and exotics.

•Predator control & defense: .300 BLK offers cleaner expansion with less

overpenetration risk.

Home Defense & Penetration Considerations   

This is where the two cartridges diverge sharply. 

.300 Blackout  

•Subsonics penetrate less than typical 5.56 in many barrier tests

•Expanding subs limit overpenetration better than 8.6 BLK 

8.6 Blackout  

•Subsonic .338 diameter bullets penetrate very deeply (often 20–30 inches in gel depending on design)

•Excellent against barriers, but riskier indoors 

Rule of Thumb:   

•Inside homes: .300 BLK is safer and more purpose-built.

•Rural property, ranch, acreage: 8.6 BLK can be a powerful defensive tool.

Suppressors & Short Barrels   

Both cartridges truly shine when paired with a suppressor and utilized in short barreled firearms.

.300 BLK   

•Designed specifically around suppression

•Burns powder efficiently in 6–10" barrels

•Works with virtually all .30-cal suppressors and even some 9mm and .45 caliber suppressors

8.6 Blackout   

•Designed around 12" barrels 

•Flow-through suppressors dramatically reduce blowback

•Heavy bullets minimize noise even further

End Result:   

•.300 BLK is the “plug-and-play” suppressor king.

•8.6 BLK is quieter than its energy level deserves—but requires an AR-10 and proper gas tuning.

Ammo Cost, Availability & Reloading   

.300 Blackout   

•Widely available

•~$0.80–$1.50/round depending on subs or supers

•Brass is plentiful and cheap 

8.6 Blackout   

•More boutique

•~$1.50–$2.50+ per round

•Brass formed from 6.5 Creedmoor; heavier bullets increase reloading cost

Ballistic Examples (Representative Loads)   

8.6 Blackout   

From 12" barrel, 100-yard zero

Bullet	Velocity	Energy	Drop @100	Drop @200
300 gr Sub	~1050 FPS	~733 ft-lbs	0"	-26 to -30"
350 gr Sub	~1000 FPS	~778 ft-lbs	0"	-32 to -36"
210 gr Super	~2200 FPS	~2250 ft-lbs	-2"	-15"

.300 Blackout   

From 8–10" barrel, 100-yard zero

Bullet	Velocity	Energy	Drop @100	Drop @200
190 gr Sub	~1050 FPS	~463 ft-lbs	0"	-28 to -32"
220 gr Sub	~1000 FPS	~489 ft-lbs	0"	-34 to -37"
125 gr Super	~2200 FPS	~1300+ ft-lbs	-1.5"	-12"

 

Which Should You Choose?   

Choose .300 Blackout if you want:   

•AR-15 compatibility - wide range of magazines, components, etc

•Affordable, widely available ammo 

•Suppressed home-defense capability

•Versatile sub and supersonic use

•Low recoil and easy tuning

Choose 8.6 Blackout if you want:   

•AR-10 stopping power in short barrels

•Maximum subsonic energy

•Larger game capability (deer, hogs, black bear)

•Better wind performance at distance

•Heavier bullets that hit like a truck

Final Thoughts   

.300 Blackout remains the king of suppressed AR-15 versatility—quiet, affordable, and easy to shoot. 8.6 Blackout is the rising heavyweight of the AR-10 world—bringing massive energy and subsonic authority to short-barreled hunting setups. Both cartridges deliver when used correctly.

Find your perfect load—subsonic or supersonic—at True Shot Ammo, where we keep both calibers in stock and ready to ship fast.