| STG-556 | |
| Origin: | United States |
| Type: | Assault rifle/Semi-automatic rifle |
| Is Ranged: | Yes |
| Designer: | Steyr Arms |
| Manufacturer: | Microtech Small Arms Research |
| Production Date: | 2007-15 |
| Number: |
|
| Variants: | See Variants |
| Weight: |
|
| Length: |
|
| Part Length: |
|
| Cartridge: | |
| Action: | Gas-operated, rotating bolt, short piston drive |
| Feed: |
|
| Sights: |
|
| Ref: | [1] [2] [3] [4] |
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]
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]
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]
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.
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]
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]