STEYR AUG; This Bullpup's No Dog

by Peter Kokalis, Technical Editor for Soldier Of Fortune magazine

 
 Bullpup suggests a dog, and the turbulent field of military small arms certainly doesn't need any more of those. What it does need is an accurate, lightweight, lethal rifle to put in the hands of well-trained infantrymen. The Bullpup assault rifle may be part of the answer. Certainly bullpups - those odd looking, space-age, smoke-poles that seem to have all the conventional parts in unconventional places - are not the perfect combat weapons for all occasions, but they have their military applications. And technical advances in bullpup design are rapidly making the weapons common sights in world hot-spots.

It's easy to tell when you've got a bullpup in your hands. It may not be so easy to tell that you're necessarily holding a military rifle. The magazine is in the buttstock and the trigger is halfway down the barrel. It seems odd, but there's no denying it's compact. A Steyr AUG bullpup with a 16-inch barrel is a foot shorter than the standard service M16.

Bullpups are bastard children. Championed by the British throughout the 20th century, bullpup rifles have never been much of an enticement to the U.S. military. In August, 1902 British engineer J.B. Thorneycroft presented a prototype bolt-action rifle to the British War Office for consideration by the Small Arms Committee. In trials it was not impressive, and all official interest in the Thorneycroft design ceased by 1903. During the early part of 1944 work started at Enfield on the design of a new bullpup sniper rifle. Called the Sniper Rifle Experimental Model I (SREM I), the weapon featured a radical design. The bolt traveled in a metal housing inclined 12 degrees below the bore axis. The bolt was operated by a pistol grip which carried an arm engaging a cammed slot on the right side of the bolt. Rearward movement of the pistol grip first rotated the bolt to unlock it and then retracted it. But military weapons technology was firmly dedicated to self-loading rifles, and the bullpup sniper rifle project was abandoned in 1945 at the war's end. Despite the slide into post-war obscurity, the early research had sparked some continuing interest.

Early interest culminated in the controversial, ill-fated British EM-2 rifle which was effectively torpedoed by the Americans in the 1952 international trials held at Aberdeen Proving Ground. Refusing to throw in the cleaning rag, the British have ignored American obstinacies on the issue and recently adopted the Enfield Individual Weapon (IW) and Light Support Weapon (LSW). Both are Bullpups.

Some Bullpup fervor did manage to cross the channel. In Belgium, FN produced a prototype carbine (serial No. 3) which was a bullpup design by Deiudonne Saive. But the project was subverted by the dictatorial Director General of FN, Rene Laloux. French weapons engineers took a long look at bullpup technology and produced their own prototypes. One of these - the French FAMAS - is a general issue weapon in French Army units.

Using the Johnson/Stoner rotary bolt, the Enfield EM-2 layout and a host of carefully considered innovations, the Austrian firm of Steyr Daimler Puch, AG, has fielded a bullpup called the AUG (Armee Universal Gewehr [rifle]). Adopted by the Austrian Army in 1977 - where it is called the Stg 77 (Sturmgewehr [assault rifle] 77) - it has become one of the most familiar bullpup weapons in the world. The AUG is now available in both military and semiautomatic-only versions in the U.S.

The bullpup's salient feature is compactness. By definition, a bullpup's barrel group is moved well back into the stock and action and magazine are placed behind the trigger assembly. Ejection of spent cartridge casings occurs close to the shooter's face, and some critics claim bullpups are inappropriate for left-handers. Other critics - particularly with combat experience in confined areas - claim the bullpup design forces a soldier to expose too much of his body when firing around corners. But bullpup fans have their own reasoned response to all that.

Only 20 percent of the world's population is left-handed, they argue, and most of them can be trained to fire effectively from the opposite shoulder. Even southpaws who can't manage the switch can be equipped with bullpups modified to accommodate them. Both the Enfield IW and the Steyr AUG feature left-side ejection options and the FAMAS has two ejectors which work to throw the case through either a left or right ejection port, depending on which one the shooter selects. Certain combat types who favor bullpups say shooting around corners is not healthy, so soldiers armed with shoulder weapons should be taught not to do it. The argument for and against bullpup designs continues.

Meanwhile, the development process that brought the weapons into active service is interesting. The Steyr AUG was developed by the Austrian Office of Military Technology under a project headed by Colonel Walter Stoll. By the end of the 1960's it was apparent that the international trend in military small arms was moving toward lighter and more compact rifles. NATO's 5.56x45mm cartridge was chosen as a proven performer in combat and Britain's EM-2 bullpup configuration was picked for compactness and ease of handling. Interchangeable barrels were specified to provide a submachine gun, carbine, assault rifle, sniper rifle and light support weapons in a basic bullpup system.

Austrian military trials then compared the AUG with the FN FAL (Austrian Stg 58 in 7.62mm NATO), the Czech Vz58 in 7.62x39 ComBloc, and the 5.56mm NATO FN CAL and Colt M16A1. The AUG proved to be at least as reliable as any of its competitors. It also proved to be superior in accuracy potential, target acquisition, handling characteristics, and full-auto fire controllability. In short, the AUG proved to be a winner.

Now in service with the Austrian Federal Army for more than eight years, the AUG has also been adopted by Saudi Arabia, Oman, Tunisia, Malaysia, Djibouti, and Morocco. It is also used by the U.S Navy Seals, the British SAS, and the Cambridge (England) police. Australia is currently conducting comparison trials in an attempt to decide on the AUG or the American M16A2 for their troops. Austria's proven bullpup has also garnered some endorsement from the guys in black hats. Columbian M-19 Marxist rebels have also obtained a number of AUGs from Tunisia via Libya.

At first glance, the AUG appears bizarre, startling, and futuristic. A closer look reveals its sinister efficiency. From the peculiar muzzle brake to the rubbery butt plate, it is obvious that efficiency and human engineering were priority parameters in development of this particular bullpup.

 Twenty-eight machine operations shape the pressure-die-cast aluminum alloy receiver, which is finished with baked enamel. Carrying handle and optical sights are integral with the receiver casting on all but the HBAR model. The receiver itself does not carry or guide the bolt assembly. A steel barrel extension containing recesses for the bolt's and barrel's locking lugs is fitted to the rear of the receiver. The barrel extension is held in place by two, thin-walled steel tubes, flanged at each end for retention on the receiver casting. These tubes also act as bearings for the bolt carrier's guide rods. The front sling swivel is mounted on the front of the receiver and is held in place by a roll pin. A spring-loaded, button-operated barrel locking latch is also mounted to the front of the receiver and retained by a steel plate held to the casting by two screws.

The plastic retracting handle is located on the receiver's left side and is non-reciprocating. An unusual forward bolt assist is activated by a spring- loaded button on the top of the retracting handle. Depressing this button connects the retracting handle with the left guide rod, so the handle can then be shoved fully forward to place the bolt into battery. Locked this way, you can ride the retracting handle slowly forward for silent cocking.

Seven locking lugs are machined into the rotary bolt, and an eighth lug is on the extractor. The ejector is a spring loaded bump-type. Extractor and ejector positions are reversed on the left-handed shooter's bolt.

Like nearly every other modern self-loading rifle, the bolt rotates by camming action. But leave it to the AUG to arrange the machinery in a completely different way. Retained by a roll pin and held in the up position by the firing pin, the cam-pin is set into the rear of the bolt.

Since the receiver is an aluminum casting and wouldn't hold up well to the slamming action of the cam-pin, a steel pressing with a cut-out cam-path sits on top of the bolt body. That pressing rotates the bolt by guiding the cam-pin through the bolt carrier's cam-slot. The firing-pin spring hooks around a nub on the end of the cam-plate, and the plastic guide plug friction fits inside the spring. A slot in the cocking piece allows the firing pin to protrude and hold the cocking piece in place at the end of the bolt carrier. A small roller mounted at the top rear of the bolt carrier eases its movement back and forth in the stock body.

Two hollow steel guide rods brass-brazed to the bolt carrier contain the two recoil springs. They are not normally removed for maintenance. During recoil, the return springs are compressed against two solid steel rods permanently mounted inside the stock assembly. Guide rod tubes are chrome plated. The gas piston drives the bolt group backwards by means of the piston furnished by the right-hand rod. The left-hand rod bears retracting handle pressure when they are connected by the forward assist button. Should the gas cylinder become clogged, the tip of the left hand guide rod can be used as a reamer to remove excess fouling. That may seem overly complicated, but it's not. The AUG has been carefully engineered to avoid excessive complication. It's also been engineered to provide the soldier or policeman with several weapons in one.

AUG is a system. Four different barrels fit any receiver in a matter of seconds. That makes four different weapons.

All barrels are constructed of high-quality steel by the cold-hammer forging process developed by GFM of Steyr, Austria, and bores and chambers are chrome plated to increase barrel life. Each barrel has eight lugs around the chamber end which engage the receiver's barrel extension. As the bolt engages the rear of the barrel extension, the cartridge is loaded into the chamber without stress on the receiver body.

Barrels have six grooves with a right-hand twist of one turn in nine inches. Steyr believes this is a better compromise for use with both M193 and the new M855 (SS109) ammunition. Barrels with a 1:7 twist can be obtained on special order.

An exterior sleeve sweated onto the barrel contains the gas port, piston, cylinder, gas regulator, and the vertical fore grip hinge assembly. Three M16 style split rings seal the chromed piston, and the return spring is attached to the piston. Gaps on the rings (washers) should always be positioned so they remain separated in use.

There are three gas regulator positions. Position 1 (small dot on the gas cylinder) is the normal setting and permits the largest amount of gas to escape into the atmosphere. Position 2 (large dot on the gas cylinder) diverts more gas into the system for adverse conditions or extreme fouling. Position GR blocks gas escape for firing blank (ballistite) cartridges to launch rifle grenades of the non-bullet trap type. In the GR position the rifle cannot cycle. To adjust the regulator, pull out the top of the gas plug and rotate it until the ball detent is aligned with the desired position.

The vertical foregrip is also used to rotate the barrel and withdraw it from the receiver during barrel changes. It provides sufficient leverage to extract a fouled barrel and prevents the unintentional obliteration of one's fingerprints by hot barrel steel.

Want an SMG? Crank on your 14-inch barrel and your AUG is a submachine gun with an unloaded weight of 6.7 pounds and overall length of 25 inches. As a safety precaution, the vertical foregrip on this barrel will not fold forward. It would extend beyond the muzzle, and there are any number of dolts who would blow away their hands, provided the opportunity. The muzzle device on this barrel is a simple, open, four-pronged affair that offers more than sufficient muzzle blast and flash to frighten off anyone you may have missed with the bullet.

AUG flash suppressors work, but they're machined like watches. Muzzle devices on the 16-inch and 20-inch barrels have three open prongs. Slots cut on top and each side control muzzle climb and avoid stirring up dust. However, flash characteristics are excellent, and the brake mildly affects muzzle climb. That's all the soldier needs to know. Internal threads cut in the device probably accept blank firing adaptors. But for all one can deduce from the Steyr English user's manual - written with the style, grammar, and spelling of a 1950 Japanese camera manual - they might hold small light bulbs. Closed bird-cage-type flash suppressors are also available on special order.

 The 24-inch barrel's muzzle device is even more bizarre. It looks like abstract metal sculpture. A closed-type device, Steyr machines its complex shape out of a single block of metal. Two large ports on each side and three small holes in front effectively control muzzle climb. But it is the exterior of the brake that is threaded to accept blank firing devices and grenade launching equipment. All AUG muzzle devices are threaded to the barrel. They are also supplied with plastic protective muzzle covers which should be trashed immediately, since they serve only to trap and retain moisture in the bore. In combat, they are invariably forgotten and shot off.

The 24-inch barrel and HBAR stock form a multipurpose weapon within the AUG system. With the strong Steyr bipod, the HBAR is adaptable to either sniping or LMG deployment. Well-designed, sturdy, and mounted close to the muzzle, the bipod's legs elevate and lock like the Mk I Bren bipod. When this barrel is used in the mode of a light support weapon, an open-bolt firing kit can be fitted to avoid cook-offs during sustained fire. This weapon is designed to replace a lot of battlefield hardware.

But you can't follow with the bayonet. The Austrian Army thinks bayonets are archaic and inhumane. Barrels don't even have studs for bayonets. But multipurpose and lightweight bayonets are available to other users. A stud clamps on to mount them.

Aside from the absence of a bayonet lug, the "real rifle" fans don't like the looks of a weapon that is all stock. You don't see much else on an AUG. But part of the beauty of the AUG is the way the stock encloses and protects all the weapon's operating parts. And since it's almost all high-impact plastic, there's no trouble in supplying it in military green, black (U.S. law enforcement version), and desert tan (Saudi contract).

The stock covers nearly everything that can be damaged on an AUG. Two plastic halves of the stock are held together by a unique friction process using pressure and vibration. The stock includes a large - and of course, unconventional - trigger guard on the pistol grip. It's just like a normal trigger guard, except it holds the whole hand instead of one finger.

The stock holds two steel operating rods in guides on either side of the magazine well. They connect the trigger to the firing mechanism. Immediately above the pistol grip a plastic crossbolt safety holds the trigger rods. Press to the right for the "safe" position (white dot) and left for fire (red dot). The crossbolt's disassembly lock pin retains the bolt and receiver groups. Find that lock pin just forward of the magazine well and press it to the right to remove these components from the stock housing.

On the bottom of the stock, behind the magazine well, sits the magazine catch release. It is ambidextrous in the sense that left and right-handed shooters have equal difficulty reaching it in the firing position. Unfortunately, it's hard to put the release anywhere but behind the magazine well. Above the magazine well are two ejection ports (for left and right-handed shooters), one of which is always covered by a removable plastic plate.

Behind the magazine well, the shoulder butt portion of the stock assembly contains the hammer mechanism module and the rear end of the bolt group. A hook on the front of the butt provides a hand rest when firing the heavy barrel off the bipod in the prone position. At the rear of the butt-section a compartment holds a cleaning kit which consists of an oil bottle, nylon and brass brushes, a cleaning rod tip, cleaning paper, and a nylon corded pull-through. Olive drab in color, the butt plate is made of synthetic rubber which offers good adhesion to the shoulder. It is held in place by the rear sling swivel's locking pin.

Contained in an open-topped plastic box, the modular hammer mechanism is fabricated entirely of plastic, except for pins, springs, the drop safety, and the lock-bolt latch. Even the hammer is plastic. And yet, according to Austrian tests, the mechanism will withstand more than 100,000 firing cycles before failure. And some complained about unconventional plastic furniture on the M16.

If you really want to see "unconventional", try to find the selector lever on an AUG. There isn't one. Just pull the trigger a short distance to the first sear stop for semiauto. Further rearward travel to a second pressure point operates the sear in the full-auto mode. With the trigger fully depressed, neither the disconnector or bolt slide can engage the hammer's sear notch. A plastic automatic fire lever, which operates like an auto safety sear, prevents firing until the bolt is in complete battery. This component is missing from the semiauto-only police version. Typical trigger-pull weights are a crisp, but heavy, 9 lbs.

Permanently fixed combat optical sights are another space-age feature of Austria's issue rifle. The AUG is equipped with a 1.5x optical sight (made by Swarovski Optik of Tyrol, Austria) designed for today's typical battle ranges of zero to 300 meters. The military version has a thick, black ring-reticle. It can be used as a rangefinder since a standing man will just fill the inner diameter of the reticle at 300 meters. The law enforcement version has a small black dot in the center which permits more precision in aiming. Windage and elevation knobs can be adjusted for initial zero, but after that, no adjustments are required out to 300 meters. But if the scope fogs or breaks, the soldier isn't out of luck. Open emergency sights have been cast into the top of the scope tube. Fixed blade front sight and square notch rear sight have three illuminated dots (one at the front blade and two at the rear) for use at low light levels.

But the optical sight should be used first in low light. It's designed for twilight conditions. Austrian Army trials proved the 1.5x scope was not only rugged, but as the shooting environment becomes more difficult, its advantages over iron sights become more obvious. Tested under time, pressure, poor target/background contrast, dawn and dusk, flare illumination, and long ranges, AUG optics gave improved hit potential over iron sights. All receiver castings except the HBAR feature the built-in scope tube.

The HBAR (Heavy-Barrel Assault Rifle) receiver casting has an integral universal scope base which accepts NATO mounts to accommodate night vision equipment and telescopic scopes for the sniping role. Mine is fitted with the high-quality Kahles ZF69 6x42mm scope with a carrying handle attached to the upper ring halves. The reticle pattern is that used by the German military since World War I - a single, thick, pointed post at the bottom of the field of view with horizontal slide bars and stadia lines. Although never popular in this country, this format excels in subdued light and offers faster target acquisition than standard cross-hairs. A formidable combination when mated to the AUG HBAR.

Since everything on the AUG is more or less astounding or different, you wouldn't expect to slap an Adventure Line M16 magazine into the magazine well - and you don't. Except the follower spring, the magazine components are entirely plastic. The waffle-pattern magazine body is the strongest I've ever seen. Especially noteworthy is the magazine's transparent body. While not crucial, it's at least comforting to count remaining cartridges. Two capacities are available: 30 and 42 rounds. As with all bottom-fed light machine guns using large-capacity magazines, the AUG HBAR will monopol on the 42-rd. box when fired from the low prone position or off the bipod.

The gas-operated AUG fires from the closed-bolt position, except when the open-bolt kit is installed. Pulling the trigger presses the hammer mechanism slide rearward by action of the sear lever. This permits the hammer to rotate upwards, powered by its two springs, striking the firing pin which moves forward to ignite the primer. Propellant gases flow through the barrel's gas port into the gas cylinder, driving the piston rearward against the right guide rod. After a movement of about 7mm, the bolt is rotated by the cam pin moving in the bolt extension and carrier slots. Extraction and ejection of the empty case occur during the bolt group's continued rearward movement. The hammer is rolled back and will stay locked if the trigger has been pulled to the first stage only.

After the bolt carrier reaches the end of its rearward travel, it is driven forward by the two recoil springs within the guide rod tubes. A fresh round is stripped from the magazine and the cam pin rotates the bolt into the locked piston. In semiautomatic mode, the slide piece presses the automatic fire lever down, and the hammer becomes locked by the disconnector lever. Releasing trigger pressure will transfer the hammer lock from disconnector lever to the slide piece. When the trigger is pulled past the second pressure point, neither slide piece nor disconnector lever can prevent the hammer from rotating upward again.

After the last round has been fired, the magazine follower presses up a lock bolt latch on the front of the hammer mechanism module to hold the bolt group to the rear. But there is no release button, and the cocking handle must be retracted to release the bolt group after a fresh magazine has been inserted - a minor irritation for those accustomed to M16 and Beretta AR70 series weapons.

To field strip the AUG, first retract the bolt, remove the magazine, and make certain no cartridge remains in the chamber. Press the barrel locking latch downward, rotate the barrel to the right, and withdraw it from the receiver. Press outward on the gas plug's latch and rotate the plug until the cut on its lower rim is aligned with the retaining stud on the barrel's sleeve assembly. Withdraw the gas plug. If badly fouled, the piston and spring may have to be driven out with a small brass drift punch from the rear end of the cylinder or driven out using the end of the right guide rod.

Allow the bolt to slide forward smartly. Do not release the trigger, or the hammer will roll upward preventing removal of the hammer mechanism. Press the stock's cross-bolt disassembly lock-pin all the way to the right and remove the receiver and bolt groups from the stock assembly. The receiver requires no further disassembly.

Then, take the bolt group, grasp the rear of the firing pin, rotate it 90 degrees counterclockwise, and pull it out of the rear of the bolt carrier. Depress the cam-pin so the bolt, bolt extension, firing-pin spring, and plastic plug can be removed. The cocking piece will then drop away from the bolt carrier. Push in on the dimple of the butt plate, and pull out the rear sling swivel pin. Lift the butt plate, and withdraw the hammer mechanism module.

After cleaning, lightly lubricate the exterior metal surfaces, the bore, and bolt group. Do not lubricate the gas plug, piston, or cylinder regardless of instructions to the contrary in the Steyr manual. Oil in the gas system only bakes to a varnish finish and accelerates fouling. Most fouling is restricted to components in the gas cylinder, and they should be cleaned with appropriate steel brushes and scrapers.

Reassemble in the reverse order. After the hammer mechanism has been placed back into the stock (with the hammer cocked), depress the plastic retaining bolt lock, and press in the rear sling swivel pin all the way to its second notch. Check the weapon for proper functioning after complete reassembly.

 More than 1,000 rounds of Lake City '77 M193 ball ammunition were pumped through my two AUGs- an HBAR (24-inch barrel) and a selective-fire police model with 14-, 16-, and 20-inch barrels. There were no stoppages of any kind. The bolt failed to hold open after the last round on three occasions. The magazine follower propels the lock-bolt latch upward, and this problem is usually associated with magazine follower springs of marginal strength.

By the way, fresh magazines must be slapped hard when inserted, or they will not properly engage the magazine catch.

The ejection path is consistently high and to the rear - about 8 to 10 feet back of the firer. Ejected cases frequently strike and mildly scuff the stock to the rear of the ejection port with no ill effect.

Ergonomics are superb, and felt recoil is nonexistent. And a magazine or two will allow you to master the trigger system. At first you want to pull right past the first pressure point into the full-auto mode. A little practice gives easy discrimination between semiauto and full-auto fire.

Burst fire, of course, is more effective than hosing with automatic small arms, and controlled bursts are easy with the AUG. M193 ball produced about 750 rpm, and experienced operators could fire two-shot bursts without effort (cyclic rate varies from 650 to 850 rpm depending on ammunition). Bursts are best kept to two shots with the 14- and 16-inch barrels, because the third round in selective fire will pass above and to the right of a man-sized target at 75 meters. But effective three-shot bursts are possible at this range with the 20-inch barrel. The HBAR version can be used for effective burst fire out to 300 meters.

When sniping with the HBAR, I got better accuracy without holding the foregrip. The support hand should be placed under the magazine catch above the butt hook when firing off the bipod in the prone position.

Longer 20- and 24-inch barrels will shoot two MOA at 100 meters every time. Hit probability is also high with the 16-inch barrel - my personal favorite, since it combines compactness with undiminished hit potential at normal engagement distances.

But unless you plan to spend most of your life breathing exhaust fumes inside a Panhard AML 245 Armored Car, you can forget about the 14-inch barrel, in my opinion. It's a flame thrower with the report of an elephant rifle.

I detect no major faults in the Steyr AUG system. All who participated in the SOF test and evaluation praised its balance and handling characteristics. It's a stunning triumph and complete vindication of the bullpup concept properly executed. In particular, the AUG 1.5x scope offers a true vision of the future. Hit probability and the speed of target acquisition are enhanced significantly by this sturdy carrying handle. You can expect to see more optics of this type on assault rifles of the future.

I would not hesitate to carry an AUG into battle.

Selective fire versions of the Steyr AUG and all its accessories are available in the United States to government and law enforcement agencies only, through the police distributors of Gun South, Inc., its exclusive importer. A semiautomatic-only version is available from Interarms. Ltd.

 

first published in the February 1985 edition of Soldier of Fortune Magazine