Heresy Design was born during the Covid pandemic. Birthed by the same crew that brought us the extraordinary gas piston-driven rifles of PWS (Primary Weapon Systems), Heresy Design has as its mission to bring to market innovative and cost-effective gun gear that you can’t find anyplace else. Where many modern gun companies are formed by entrepreneurs who are financially savvy but gun ignorant, the brain trust at Heresy Design draws from a deep well of practical experience making some of the finest combat rifles in the world. For their artistic medium, these ballistic savants chose the Steyr AUG.

Heresy Design AUG Conversion Kits

Heresy Design now offers the barrels, accessories, and conversion kits to take your AUG to radical new rarefied spaces. Thanks to these guys, your favorite AUG is now as versatile as the M4 only with a great deal more style. I was just giddy.

The Gracious Host

1977 saw Saturday Night Fever and Star Wars dominate the local cineplex, while the first Apple II computers revolutionized the personal workspace. 1977 was the year Elvis Presley gracelessly perished on the toilet at Graceland. Also in 1977, Steyr Arms launched the most advanced assault rifle in military history. The Armee-Universal-Gewehr (literally “Army Universal Rifle“), changed the way the world looked at combat weapons.

The AUG was officially known as the StG 77. In addition to sporting a radically-advanced polymer magazine and furniture, the AUG was also the first standard-issue military rifle to incorporate a built-in optical sight. And then there was that weird bullpup design.

Nobody is really sure where the term “Bullpup” originated. Patented in 1901, the British bolt-action Thorneycroft carbine was the first military weapon designed with the receiver behind the trigger. By the time Steyr launched the AUG some 76 years later the concept was perfected.

The Versatile, Modular AUG

Most mechanical contrivances introduced in the 1970’s have gone the way of the dodo. Consider the floppy disk, the Walkman, the video game Pong, and the Pet Rock. However, despite being 47 years old, the AUG still remains competitive with modern military small arms even today.

Modularity is the holy gospel amongst Information Age military firearms. The ideal combat weapon uses a common chassis to become everything from a pistol-caliber submachine gun to a heavy-barrel, rifle-caliber support weapon. Nobody on the planet does that quite so well as Steyr. Now Heresy Design brings all that inimitable military modularity to American civilian shooters as well.

Nowadays Steyr produces AUG rifles domestically in Bessemer, Alabama. The MSRP is $1,999.99. A little comparison shopping shows them running as low as $1,800 if you’re patient and willing to stalk your prey. Considering the technology that goes into these guns, that price is competitive with comparably refined iron.

Pistol-Caliber Particulars

For starters, Heresy offers a drop-in 9mm conversion. Steyr made something similar, but they are no longer imported. The last one I saw for sale was a cool $4,400, and the barrel wasn’t even threaded. By contrast, the Heresy conversion includes a 16.1-inch threaded barrel, a three-lug suppressor mount, and built-in accessory rails. The conversion kit includes the coolest 30-round polymer 9mm magazine insert nestled within a P-Mag chassis and a proprietary bolt assembly.

Adding a Heresy 9mm conversion to your favorite Steyr rifle lets you seamlessly run inexpensive 9mm Parabellum. That’s kind of a big deal. 5.56mm ammo is currently tough to find and expensive. However, 9mm ball remains cheap, ubiquitous, soft-shooting, and available. The nature of the Heresy conversion also readily lends itself to a sound suppressor.

With the Heresy Design 9mm conversion in place, the AUG exhibits a fresh new personality. The 9mm AUG conversion operates via unlocked blowback, so the gun’s comportment is curiously snappy. Recoil is still not real, and the diminished muzzle blast makes laying down brass an absolute joy. Additionally, you can add a suppressor painlessly via either mounting option.

Interestingly, there were certain loads the 9mm conversion devoured, and others it didn’t. Cheap 115-grain blasting ball ran fine as did 147-grain Winchester Defender hollowpoints. Lightweight 100-grain Black Hills Honeybadger antipersonnel loads often choked as did, oddly, 124-grain FMJ Winchester fare. Once I had experimented a bit to find the ammo it liked, the conversion was a wild ride.

Muffling Your AUG

Heresy also offers a drop-in barrel assembly in .300 BLK. The modular nature of the AUG design means that swapping your rifle over to .300 BLK involves nothing more than pressing a button, removing the old 5.56mm barrel, and snapping the new Heresy unit in place. The gun uses the same standard magazine, bolt, and bolt carrier assembly. The transformation literally could not be easier.

In case you’ve been living under a rock someplace, the .300 BLK is what happens when you set a .30-caliber bullet in a 5.56x45mm cartridge case. Ammunition can be found in either lightweight supersonic or heavyweight subsonic versions. The end result makes your favorite black rifle hugely more versatile. With a proper sound suppressor, the subsonic versions are delightfully quiet. Stuff your mags with the supersonic sort and you are set to put whitetail deer on table. Additionally, an economy of scale means that .300 BLK ammo is both available and affordable.

I mounted up a SIG sound suppressor and hit the range without muffs. Running subsonic loads outdoors is positively dreamy. The same rig inside preserves your hearing in a crisis. The argument could be made that a Heresy-converted, sound-suppressed AUG running subsonic .300 BLK is the ideal home defense or truck gun.

During our time together on the range, the Heresy .300 BLK conversion ran flawlessly with everything except gaping hollowpoints. The three-position gas system on the barrel assembly is readily adjustable with nothing fancier than a standard set of human fingers. Ours ran great right out of the box. The end result hits hard and is absolutely addictive.

How Low Can You Go?

Another nifty trinket on the Heresy Design website is a drop-in 14.5-inch barrel assembly. Inflation has taken the teeth out of the onerous $200 NFA transfer tax to the point that it isn’t the disincentive to building your own registered short-barreled rifle that was once the case. If you have two C-notes to burn and are fairly patient, you can do a BATF Form 1 on your AUG and cut the barrel back as far as you wish. The innately compact nature of the bullpup design means that the AUG with a 14.5-inch barrel is markedly shorter than a typical M4 with the same length tube. With the Heresy 14.5-inch barrel in place, the resulting ultra-compact AUG is almost concealable. Whether you are a spy, a cop, or simply a security-minded individual, the resulting stubby AUG will ride comfortably in some of the handiest spaces.

Like all AUG barrel assemblies, swapping one for the other is painless without tools. The Heresy barrel is threaded 1/2×28 for a sound suppressor if desired. The end result is unprecedented versatility.

Running the super-short barrel on your AUG is a wild ride. Thanks to the telescoped nature of the design, all that muzzle chaos is released just ahead of your nose. The cumulative result will cleanly part your hair and reliably clear your sinuses. However, this thing runs like a lawyer after money.

Grand Scheme

Heresy Design also offers a drop-in extended safety as well as an oversized magazine release that both conspire to make these great guns even greater. Installation is a breeze, and the end result is faster and more efficient than the stock weapon. The quality of all of the Heresy Design kit is unimpeachable. I would put it all on par with or better than the factory stuff. Everything was a seamless fit into a semiauto American-made AUG, though the 9mm conversion didn’t care for the selective fire GI version of the gun. Nothing fit my old MSAR STG-556, but that is to be expected. The specs are a bit different on that rifle.

Thanks to Heresy Design you really can invest in a single rifle chassis that can be all things for all missions. Running a quality sound suppressor and subsonic ammo, both the 9mm and .300 BLK rigs are stealthy, comfortable, and cool. The 14.5-inch barrel on an NFA-registered receiver is as small as current technology can make an effective combat rifle. The bullpup geometry allows for a package that still produces decent mil-spec velocities while remaining markedly more compact than the GI-issue M4 with its 14.5-inch tube.

I used to think that the M4 was the undisputed king of modularity. However, once Heresy Design has had their way with it, the AUGmented AUG does everything an M4 might only shorter and with a lot more class. Once you’ve invested in the host rifle, you can add barrels and bits as the budget allows. Once fully fleshed out, the end result really is everything for everybody.

Running the AUG: Manual of Arms

The manual of arms of the AUG is unique. However, it’s not like time on the range is actually work. An afternoon’s worth of trigger time will have you running the Heresy-enhanced AUG rapidly and well. Whether you secure the gun behind the door to your bedroom closet or in a bugout bag in your minivan, the end result is like a chaos vaccine.

The market for cool tactical weapons is robust these days, and American civilian shooters are the beneficiaries. Heresy Design conversions are reliable, well-reasoned, and unique in the marketplace. If you’re the sort who marches to their own beat and doesn’t mind being extra awesome at the range, Steyr and the mad geniuses at Heresy Design can scratch your itch.

For more info on the Heresy Design AUG Conversion Kits, visit heresydesign.com.

Technical Specifications

Performance Specifications