PROFILBARU.COM

STG-556
STG-556
Type	Assault rifle/Semi-automatic rifle
Place of origin	United States
Production history
Designer	Steyr Arms
Manufacturer	Microtech Small Arms Research
Produced	2007-15
No. built	1000 (Limited edition STG-556); 232 (STG-556 rifles with an 18.5" heavy barrel); 500 (STG-556 Gebirgsjäger);
Variants	See Variants
Specifications
Mass	Empty: 3.62 kg (8.0 lb);
Length	26 in (660.4 mm); 27 in (685.8 mm); 31 in (787.4 mm);
Barrel length	14 in (355.6 mm); 16 in (406.4 mm); 18.5 in (469.9 mm) (only for .300 Blackout); 20 in (508.0 mm);
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 system	10/20/30/42-round detachable box magazine; 30-round magazine (7.62/5.45 variants); STANAG magazine (XM17-E4 only);
Sights	1.5x optical sight; Can have various scopes/sights installed via picatinny railing;
References

The STG-556 is a Steyr AUG clone formerly manufactured by Microtech Small Arms Research (MSAR).^[5] It was available in civilian and military/law enforcement (select-fire) variants.^[6]

History

It was introduced at the 2007 SHOT Show. The first few STG-556 rifles were chambered in .223 Caliber.^[4]

In July 2012, MSAR resurfaced with a new STG-556 rifle variant known as the STG-E4.^[7]

MSAR closed down permanently on March 20, 2015.^[8] No specific reasons were stated on their website, but it is well known that Steyr setting up a US based manufacturing arm, producing genuine Steyr AUG firearms, all but eliminated the need for anyone to buy a clone.^[5]

Design

The STG-556's design was based on the original Steyr AUG since the patents expired at the time.^[6] The frame was made on 7075 T6 aircraft-grade aluminum^[9] and made from cast, unlike the TPD AXR as it was made through forging.^[10] It was available in black, tan and green finish.^[9]

It features a bolt release as seen on the M16 rifle^[6] and a forward assist.^[9] Otherwise, the STG-556 retains the features similar to the Steyr AUG, such as having the quick-change barrel option and the ability to change which side the weapon ejects from by changing the bolt out for a right or left side bolt respectively. The STG-556 has a right-side ejector.

When using a suppressor or low-pressure ammo, the gas regulator needs to be adjusted to allow more gas to be used to fire ammo.^[11] The gas regulator positions consist of "S", which is the normal setting and allows large amounts of gas to escape from the rifle.^[12] "H" diverts more gas into the rifle to allow the STG-556 to be fired in adverse conditions or extreme foulings.^[12] "GR" diverts gas into the system to fire blanks in order to launch rifle grenades.^[12]

The STG-556 uses a short-stroke gas piston. The rifle can be converted from either having a telescopic sight or a MIL-STD-1913 rail.^[6] Various accessories can be attached on the rail.^[13]

The STG-556 uses magazines similar to those used by the Steyr AUG (10/20/30/42),^[14] being made up of “radel” (polyphenylsulfone).^[11] The rifles can also take 30-round STANAG and Magpul PMAG magazines.^[10] The XM-17E4 variant can use STANAG magazines.

Most STG-556 rifles made in 2009 did not allow to use AUG-type magazines unless the three ribs on top were professionally filed off.^[12] All STG-556s without a forward-assist mechanism can take AUG magazines.^[12]

The barrel can accept a blank adapter or a suppressor.^[15]

Variants

STG-556 Limited Edition

A limited edition STG-556, a clone of the Steyr AUG A3, had a production run of only 1,000 rifles. There was a limited production of 232 rifles produced with an 18.5" heavy barrel after tests proved that length provided optimum accuracy over the 24" length due to barrel harmonics.

STG-556 Gebirgsjäger

The STG-556 Gebirgsjäger had a production run of 500 rifles. It was named after the Gebirgsjäger, which means Mountain Huntsmen.^[16] It was previously sold with an OD green Currahee Knife and a MSAR Pelican 1700 case.^[16]

STG-556 E4

The STG-556 E4 was introduced in 2009.^[12] It can use AR-15 and M16 magazines.^[4] For any E4s that use .300 AAC Blackout, they can use the 18.5" barrel.^[17]