Colt with .300 AAC Blackout upper, Leupold scope, and Gemtech One suppressor.
Colt with .300 upper, Leupold scope, and Gemtech One suppressor.

Articles have been written on the .300 AAC Blackout (.300 BLK) that give the history and purpose of the cartridge. I decided to put one together to see how it performed suppressed. I had some parts and a stripped BCM upper and got a barrel from Brownells and a forend from Diamondback. I was able to assemble a pretty decent upper and mounted a .300 BLK scope from Nikon.

I sent the upper to Birdsong for a Black-T camo job that matched the existing lower on a Colt 6920. I’ve used Birdsong’s Black-T on many of my guns for 25 years and think it’s the best finish available—better lubricity than oil and great corrosion resistance.

This AR has some additions: a Giselle SSA trigger, BCM charging handle, and enhanced trigger guard. The scope has stadia lines for ranges out to 500 yards. I have a Gemtech One suppressor, so I bought a QD mount and was set. I took off the 5.56 upper from my Colt 6920 and replaced it with the .300 upper. Fifteen seconds, different gun.

Birdsong camo finish is aesthetically pleasing and durable.
Birdsong camo finish is aesthetically pleasing and durable.

The Colt 5.56 upper is also equipped with the Gemtech suppressor bolt group—a 90-degree rotation of one screw changes it from unsuppressed to suppressed, and the QD Gemtech mounts are the same on both guns, so it can also be fired suppressed with 5.56.

In supersonic loadings, 300 blackout ammo is about on par with 7.62×39, the AK/SKS round. If I recall correctly, Russian military doctrine is massed rifle fire within 200 yards: Get enough troops within 200 yards, shoot a bazillion rounds, and someone is gonna die. The AK round is similar to a .30-30 Winchester—not a 500-yard sniper round, but fairly effective within its range.


I first shot the rifle unsuppressed to see how it and the scope did. I zeroed at 50 yards with Winchester 150-grain XP soft points, then used the BDC reticle to shoot at 100, 200, and 300 yards. The BDC feature worked well, but even with good ammo, it’s not exceptionally accurate—.8 inch at 100, 2.5 inches at 200, and about 5.5 at 300. That 300-yard group is center-of-man or deer, but I don’t know how much energy it has.

Gun and upper rest on Maxpedition ruck. Note effectiveness of pattern.
Gun and upper rest on Maxpedition ruck. Note effectiveness of pattern.

I then loaded a couple of magazines with Black Hills 220-grain .300 Whisper and rezeroed at 50 yards suppressed. This combination shot really well, with three, three-shot groups averaging .5 inch. I also shot three groups with Gemtech 187-grain polymer tip subsonic, which shot .65 inch. Next I moved to 100 yards, where the 220-grain Black Hills hit 6.2 inches low—not surprising with a heavy bullet travelling at 1,050 fps. I moved the target to 150 yards and fired three rounds, which hit 26.5 inches low.


What uses would the military, police, or private citizens have for this combination? In a military application, the troop could use it with supersonic ammunition for normal use, engaging targets at normal ranges. SpecOps troops could swap out the mag to subsonic, slap a suppressor on the muzzle, and be able to discreetly kill enemy fighters.

I thought of the movie Lone Survivor, where the SEAL team was compromised by shepherds. If rules of engagement allowed, the shepherds could have been taken out quietly, allowing the SEALs to complete the mission. On covert missions, sentries, dogs, etc could be eliminated with less chance of discovery, increasing the chances of success.


Both subsonic rounds tested were reliable and accurate.
Both subsonic rounds tested were reliable and accurate.

For law enforcement, I see some good possibilities. We once had to kill a couple of guard dogs prior to executing a search warrant. Our field-expedient method was effective, but certainly less humane and less efficient than a subsonic .30-caliber round would have been.

Wildlife is a problem in many cities in the west. Several small towns near my location are overpopulated with deer, and cars hit them on a daily basis. A trained officer with a short, suppressed carbine could safely, efficiently, and discreetly reduce the populations. The same would apply to cougars, bears, the odd wolf, feral dogs, and other wildlife that cause local problems.

Gemtech One suppressor works from .22 to .300 Win Mag and is full-auto rated.
Gemtech One suppressor works from .22 to .300 Win Mag and is full-auto rated.

No-knock search warrants are relatively rare, but if a team had to execute such a warrant, the overwatch troop could use a suppressed .300. If the entry team were compromised on approach by an armed suspect, the object of the warrant might not notice that their rear guard was gone. If the lives of hostages were at stake, this could prove crucial.

For an entry team, the heavy, slow bullet from a suppressed gun should be very effective. Team members wouldn’t need to worry about hearing loss, and officers could communicate more effectively. For a police department, a designated marksman-trained officer or two with a .300 BLK upper and optic available, it would be a low-cost and effective addition to have available if the need arose.

One lower, two uppers, and optics -- several missions.
One lower, two uppers, and optics — several missions.

I do a lot of training in the oil fields of Alaska. Pump stations can be full of combustible vapors, so a suppressor would probably eliminate the danger of an explosion. The same would apply to drug units searching meth labs. For all the above reasons, suppressors and subsonic ammunition are almost must-haves.


For private citizens, the cartridge would be a dandy game-getter in a long-term survival situation. My preparedness plan is to be as low profile as possible for as long as possible. If potential enemies were around, taking a deer or turkey with almost no noise would be very useful.

There are lots of each critter where I live, and shots within 50 yards present themselves every day. I know, a crossbow, slingshot or compound bow can do the same thing, but I’m neither David nor William Tell. A rifle works better for me. [If you plan to use a suppressor, check your state game laws carefully before you go out hunting this fall. Some states do not allow suppressed rifles for hunting.]


Gemtech, Winchester, and Black Hills .300 BLK ammo. Author stocked 100 rounds of each for special purposes.
Gemtech, Winchester, and Black Hills .300 BLK ammo. Author stocked 100 rounds of each for special purposes.

For me, the .300 BLK is a niche gun with limited special purpose. I stocked 100 rounds each of the Winchester XP, Gemtech 187-grain subsonic, and Black Hills 220 grain. I have quite a bit of brass and a bunch of Nosler 180-grain partition bullets and will work up a good subsonic load this winter.

I keep the 5.56 upper on the Colt AR but have the .300 BLK upper handy. I replaced the Nikon with a smaller, lighter 1-5X Leupold zeroed for 50 yards. I keep one magazine with the same Birdsong finish as the lower to avoid mistakes, loaded with the Black Hills 220-grain round. If the grid goes down and an edible creature appears, no one will know I have obtained supper.

Jeff Hall is a former soldier, retired Alaska State Trooper, and martial arts grandmaster. He can be reached at [email protected].


(605) 348-5150

(877) BRAVO-CO

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(208) 939-7222

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