SOF Week

CORVUS DEFENSIO: Bringing the Steyr AUG to the 21st Century

The Steyr AUG is a great rifle, but it somehow got stuck in the 70s’ when the select fire StG77 (StG is short for Sturmgewehr; German for assault rifle) was introduced with the Austrian Bundesheer (Army). There are licensed copies and clones, but the US-made MSAR did not differ significantly from the original design. The Steyr AUG A2 introduced a top rail and the A3 a bolt stop, but external as well as internal mods to the gun are rare and in between (CQC kit, Ratworx & Suarez parts). Thales did a complete rework of the Australian made F88 and introduced the modified F90 in the process. Mods from Steyr itself? Enjoy the silence…

Therefore a new company got in the game. Based in Vienna, Austria, its mission is to bring 21st century accessories to the end-users of the Steyr AUG. CORVUS DEFENSIO is tackling the deficiencies of the rifle with intelligent solutions designed by practical experience with the AUG in different environments.


One of the biggest problems of the AUG is ejecting the case into your face – which is a bullpup problem. The CORVUS DEFENSIO Case Deflector ejects cases forward or to the side and thus makes it ideal to shoot in every combat stance, from either shoulder, without any additional modifications or adaptations. Installation requires no drilling or modification to the stock as the two piece Case Deflector is simply plugged into the ejection port and tightened with two screws, the plastic stock is also protected against damage when an empty case is not completely ejected.


But CORVUS DEFENSIO is changing the whole rifle: The CORVUS DEFENSIO 35-Slot Receiver Rail offers a long, solid mounting solution for the attachment of optical aiming devices, iron sights, laser designators and other accessories.  The total length of the rail is the same as the rail length of an AR15 receiver and attached 9” (midlength gas system) railed handguard.  Unlike the AR15 receiver and handguard rails, the Corvus Defensio 35-Slot Receiver Rail is solid (monolithic) from front to rear.  Unlike the original Steyr AUG A3 rail, the Corvus Defensio Receiver Rail reaches almost to the ejection port, making it easier to use short eye-relief optics. It is equipped with two QD-Sling Swivel attachment points and an interface to directly mount ACOG rifle scopes. Integral limited rotation QD Sling swivel attachment points (also suitable for snap hooks, paracord, etc.). With much space for what the shooter needs: Keymod installation option in the front rail for mounting accessories on the sides.


Keymod is the choice of CORVUS DEFENSIO also when changing the traditional AUG grip to a rail with much more options. The CORVUS DEFENSIO Forward Accessory Rail revolutionizes the Steyr Aug’s mounting options.  Very simply, it replaces the original folding front grip and enables the mounting of a variety of accessories directly to the Keymod interface (e.g. front grips, bipods, etc.).  Direct mounting reduces weight and bulk, but if you want to use common Picatinny mounts, you can attach the Corvus Defensio 15-Slot or 4-Slot Keymod-Picatinny accessory rail sections to the Corvus Defensio Accessory Rail.


The AUG is also getting better with a new mag release: The CORVUS DEFENSIO Enhanced Magazine Release Button makes reloading faster and more reliable. When you go for limit (stress caused by competition or combat, wetness, numb or cold fingers, darkness, etc.) faulty operations with the original magazine release button may happen. Your thumb could slip aside because of the original releases’ outwardly curved form or you even might not be able to push the button far enough inside the housing because your thumb was not right in the center of it an gets caught at the stock. The issue of the original part is that the release of the magazine happens just when the button is already recessed in its port. The design of the CORVUS DEFENSIO replacement part prevents those situations reliably, thus ensuring a faster and more reliable magazine change.

CORVUS DEFENSIO also opts for a new sling mount: The CORVUS DEFENSIO Anti-Rotation Stock Cap Retainer Bolt Kit solves two problems that often occur when using the AUG professionally.  Because the original stock cap retainer bolt can be rotated around its axis, the sling can become twisted after repeated slinging and unslinging of the rifle.  This creates unpleasant pressure points on the shoulder and quick adjustable slings might also lose that function.  While the CORVUS DEFENSIO Anti-Rotation feature completely prevents twisting of the sling, the QD function allows for fast sling detachment, e.g. for disassembly and cleaning of the rifle.


All that is good already. But one of the biggest concerns shooters have with the Steyr AUG (and Bullpups in general) is the trigger system and how it performs. The original plastic trigger feels a bit like a single stage trigger with a hard pull and a creeping reset. CORVUS DEFENSIO was inspired by the idea of Ratworx and 2020 Precision to implant a standard AR15 trigger into the Steyr AUG. As it was not possible to obtain one of these triggers in Europe CORVUS DEFENSIO started to design their own Enhanced Trigger System. It´s rather tricky to accomplish a proper technical solution with a reliable trigger system that fulfills the expectations. But CORVUS DEFENSIO is on a good way to get a solution using in their opinion one of the best AR trigger systems that can be found. Namely ALG and Geissele Triggers. The fine tuning and the quality checks are still going on and the prototypes are very promising.

To draw the balance: Each item by CORVUS DEFENSIO is improving the Steyr AUG in a specific area, and as a package they revolutionize the rifle’s handling, modularity and capability. Starting October 26th, the first batch of accessories is becoming available, with more under development.



12 Responses to “CORVUS DEFENSIO: Bringing the Steyr AUG to the 21st Century”

  1. AbnMedOps says:

    “That’s the Steyr AUG. Steyr AUG is a bad MF’er. It’s made in AUSTRIA!”

  2. PL says:


  3. steve says:

    Dressing up a terrible rifle

    • Dropbear says:

      Terrible how? The Austeyr is my daily work gun and I’ve carried/used it overseas. Aside from having to work with the magazine housing behind the pistol grip and the Australian barrel removal mod (which is disappearing with the EF88 variant), I’ve found the Steyr to be a solid conventional forces rifle. Paired with a good optic ((Wildcat , ACOG, Spectre) and the enhanced performance round and in the hands of a competent firer, it’ll hold up against the M4 and similar rifles.

      • steve says:

        It is far inferior to an AR15 style rifle, ergnomics of the gun are very average, it is heavy for what it is, it is far more difficult to maintain(clean and keep shit out of the working parts). Fixed length, incapable of efficient offhand shooting(even with a case deflector as ejected cases right near your face distracting). Woeful modularity-have to dress it up with heavy ass rails, limited postitions for hands to cater for various shooti g styles, magazine release slow and inefficient. General bulk of the thing is terrible. If you think its on the same level as an m4 you are kidding, the m4 is a coventional forces weapon. Also the ef88 has had that much trimmed out of the front of it to reduce weight puts the shooters hand pretty much on an exposed barrel if he doesnt want to use a foregrip and is thus hot as shit after one mag.

      • Phil says:

        Don’t try and compare the F88/EF88 to any AR platform, it’s a good bullpup but nothing more.

  4. mark says:

    As one of the dozens of AUG owners in the US, I’m very excited for this.

    • Hubb says:

      HAHA…I’m one of the few also. That Shell Deflector and Mag Release look promising. Too bad that Value Added Tax and exchange rate make the price seem expensive.

  5. TED says:

    My left shoulder got trashed. I have a hard time holding up an M4 anymore. I really dig the AUG. These are welcomed developments.