STG-556
A Steyr AUG clone formerly made by Microtech Small Arms Research.
The STG-556 is a clone of the Steyr AUG that was previously produced by Microtech Small Arms Research (MSAR). It was offered in both civilian and select-fire military and law enforcement versions.
The rifle debuted at the 2007 SHOT Show, with the earliest examples chambered in .223 Caliber. In July 2012, MSAR reappeared with an updated variant called the STG-E4. MSAR permanently shut down on March 20, 2015. While no specific reason was given on their website, it is widely understood that Steyr establishing a U.S.-based manufacturing arm to produce genuine AUGs largely removed the market for clones.
The STG-556’s design was based on the original Steyr AUG, as the relevant patents had expired. Its receiver was cast from 7075-T6 aircraft-grade aluminum, unlike the forged TPD AXR. Finishes included black, tan, and green. It included a bolt release similar to that of the M16 and a forward assist. Otherwise, it kept many AUG features, such as a quick-change barrel and the ability to swap ejection sides by changing the bolt for a right- or left-hand version. The STG-556 ejected from the right side. When using a suppressor or low-pressure ammunition, the gas regulator needed adjustment to allow more gas; the settings were "S" (normal, venting excess gas), "H" (diverting more gas for adverse conditions or heavy fouling), and "GR" (diverting gas to fire blanks for rifle grenades). It used a short-stroke gas piston. The rifle could be configured with either a telescopic sight or a MIL-STD-1913 rail, and various accessories could be mounted on the rail. It accepted magazines similar to the Steyr AUG’s (10, 20, 30, or 42 rounds), made from Radel (polyphenylsulfone), and could also take 30-round STANAG and Magpul PMAG magazines. The XM-17E4 variant could use STANAG magazines. Most STG-556s made in 2009 could not use AUG-type magazines unless the three ribs on top were professionally filed off; all STG-556s without a forward assist could accept AUG magazines. The barrel could accept a blank adapter or a suppressor.
Variants included a Limited Edition, a clone of the Steyr AUG A3, with only 1,000 rifles produced. A limited run of 232 rifles featured an 18.5-inch heavy barrel, chosen after testing showed that length offered the best accuracy due to barrel harmonics.
Quick Facts
- Origin
- United States / Austria
- Is Ranged
- Yes
- Designer
- Steyr Arms
- Manufacturer
- Microtech Small Arms Research
- Production Date
- 2007-15
- Number
- 1000 (Limited edition STG-556) / 232 (STG-556 rifles with an 18.5" heavy barrel) / 500 (STG-556 Gebirgsjäger)
- Weight
- Empty: 3.62 kg
- Length
- 26 inch / 27 inch / 31 inch
- Part Length
- 14 inch / 16 inch / 18.5 inch (only for .300 Blackout) / 20 inch
- Cartridge
- 5.56×45mm NATO / .300 AAC Blackout / 6.8mm Remington SPC / 7.62×39mm / 5.45×39mm
- Action
- Gas-operated, rotating bolt, short piston drive
- Feed
- 10/20/30/42-round detachable box magazine / 30-round magazine (7.62/5.45 variants) / STANAG magazine (XM17-E4 only)
Facts from the source article.
Lore & Background
The STG-556 was based on the original Steyr AUG after the patents expired. Its receiver was cast from 7075-T6 aircraft-grade aluminum, unlike the forged TPD AXR. It featured a bolt release similar to the M16 rifle and a forward assist, while retaining the Steyr AUG's quick-change barrel and the ability to swap bolts for right- or left-side ejection. The rifle used a short-stroke gas piston and had a gas regulator with settings: 'S' (normal), 'H' (adverse conditions), and 'GR' (blanks for rifle grenades). It could be configured with a telescopic sight or a MIL-STD-1913 rail.
In July 2012, MSAR resurfaced with a new variant called the STG-E4. MSAR closed permanently on March 20, 2015; no specific reasons were stated, but it is well known that Steyr setting up a US-based manufacturing arm producing genuine Steyr AUG firearms eliminated the need for clones. Most STG-556 rifles made in 2009 did not allow use of AUG-type magazines unless the three ribs on top were professionally filed off; all STG-556s without a forward-assist mechanism could take AUG magazines.
Reader's Guide
The STG-556 represents a notable chapter in the history of bullpup rifle clones, emerging after the expiration of Steyr AUG patents. Its significance lies in offering a civilian-legal and select-fire alternative to the original, with improvements such as an M16-style bolt release and forward assist. The rifle's ability to accept STANAG and PMAG magazines broadened its appeal. However, the closure of MSAR in 2015, following Steyr's establishment of a US manufacturing arm, effectively ended the need for clones. The STG-556's legacy is that of a well-regarded clone that filled a market gap until the genuine article became readily available domestically. Its limited-edition variants, such as the 1,000-rifle Limited Edition and the 500-rifle Gebirgsjäger, add collector interest. The STG-556 remains a point of reference for enthusiasts of bullpup designs and clone rifles.
Did You Know?
- The STG-556 was introduced at the 2007 SHOT Show.
- It was available in black, tan, and green finishes.
- The STG-556 Gebirgsjäger had a production run of only 500 rifles.
- The gas regulator has settings labeled 'S', 'H', and 'GR'.
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