The .300 Super in a mil-spec AR-15 magazine above a .300 Blackout round. The Super offers substantially improved performance for those seeking a flat-shooting, hard-hitting .30 caliber projectile out of an otherwise standard AR-15 platform.


by John Boch
America has long been known as a place where, with a little know-how and American ingenuity, a person can build a better widget.

One of our members has done just that.

For three years, Guns Save Life member Chris Betley has worked on something better for competitive use from the 5.56mm AR-15 platform.

He’s invented a new cartridge, the .300 Super, that is notably superior to the already impressive .300 AAC Blackout that’s been taking the shooting world by storm.

Why is the .300 Super Chris Betley’s Holy Grail?

It has about 11% more case capacity than the Blackout, giving it a lot of extra horsepower (otherwise known as foot-pounds of energy) in a flatter-shooting cartridge.

Out of a 14.5” Bartlein 5R barrel (with a 1:11 quarter-twist), Betley’s .300 Super loaded with a 150gr. Sierra Match King bullet sizzles out at nearly 2500 feet per second.  He says the rifle’s 25-meter zero is also dead on at 500 meters, making it very desirable for competitive shooters or those seeking a flat-shooting, accurate cartridge approaching .308/7.62×51 ballistics with fairly tame recoil on compensator-equipped rifles.

Not only does the Super eclipse the rifle performance of the .300 Blackout, it also runs circles around the Blackout when fired from the pistol-length barrels.

Out of a 7” pistol barrel, it handles nicely, launching rounds that impact with authority while maintaining a flat trajectory.  For instance, the bullet drop from 100 to 200 meters is 1.5”, notably less than the .300 AAC Blackout.

“I needed something that would knock down a 40-pound 6-inch plate at 200-meters.  This does that and more with ease,” he said of a .300 Super loaded with a 135-grain bullet for the pistol configuration.  It sends hot lead downrange at about 2200 feet per second – out of that 7” barrel.  That’s significantly better performance and muzzle energy than a .300 Blackout from a 16” barrel.

Even better, it easily shoots under one minute-of-angle.

For dealing with asocial, two-legged varmints, the .300 Super can be loaded with Hornady GMX ballistic tip bullets which offer devastating expansion for impressive stopping power.  The same bullet will work just dandy for most four-legged critters as well.  Just don’t use it for small game.  Application of the .300 Super loaded with GMX bullets on Easter bunnies, tree rats or raccoons will leave a pink mist and bloody chunks, not tasty meat.

The great thing about the .300 Super is that like the Blackout, it works in standard AR-15 magazines and AR rifles.  The only change is the barrel.

It functions in full-auto applications as well.

Mr. Betley notes that those who are really looking for a competitive edge can use black nitrite-treated barrels.  With this new process,  shooters can pick up an additional 200 feet per second over chrome-lined barrels, which would make the .300 Super an even more awesome round.

People, including his fellow shooters on the professional shooting circuit are taking note of this new cartridge.

What’s more, so are commercial firearms companies. Our guy has already lined up a company that will produce the brass and is in negotiations with another company to handle commercial production of new ammunition.  Also, large police agencies are making inquiries as well, realizing that the new round will offer performance vastly more powerful than anything currently on the market in the 5.56mm AR-system.

For now though, he’s making the uppers on a small scale for those who seek cutting-edge performance from the familiar, America’s favorite rifle platform.

What’s it cost?  The rifles will sell for nearly three bills and the ammo will start at about $3 per round.  “Sierra Match King bullets are almost a buck a bullet alone,” Betley said of the cost per round.  Hornady’s GMX projectiles are easily $2 per round just for the bullet!

What’s his recipe?  Betley tells us he doesn’t use any of Colonel Sanders secret herbs and spices, instead relying on H110 or 1680 powder and Wolf small rifle primers.

“You’re using commie primers?” I asked him.

Betley laughed.  “They’re hard, to eliminate any chance of inertial detonation,” he said.  “And they go bang every time.”  The AR-15 has a free-floating firing pin and some softer primers, he explained, have discharged once in a blue moon when a firing pin taps them just right.

For more information on this new round, or inquiries on purchasing your own upper/ammunition/etc, contact Chris at

4 thoughts on “.300 SUPER: The Blackout Killer”
  1. Very interested in this round. Sounds like the ideal hog/deer gun for The AR platform.

  2. More information please.

    Does it require a modified mag to feed reliably like the 7.62x40WT, or does it truly use unmodified 5.56 AR-15 mags?

  3. Is there a functional subsonic loading as well? If not, it really doesn’t occupy the same niche, and should be compared against 6.5 Grendel and 6.8 SPC instead. Though the very good short-barrel performance should be applauded.

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