STG-556
{{Infobox weapon
|name=STG-556
|image=
|caption=
|origin=United States
|type=Assault rifle/Semi-automatic rifle
|is_ranged=Yes
|service=
|used_by=
|wars=
|designer=Steyr Arms
|design_date=
|manufacturer=Microtech Small Arms Research
|unit_cost=
|production_date=2007-15
|number=
- 1000 (Limited edition STG-556)
- 232 (STG-556 rifles with an 18.5" heavy barrel)
- 500 (STG-556 Gebirgsjäger)
|variants=See Variants
|weight=
- Empty: {{convert|3.62|kg|abbr=on}}
|length=
- {{convert|26|inch|abbr=on|1}}
- {{convert|27|inch|abbr=on|1}}
- {{convert|31|inch|abbr=on|1}}
|part_length=
- {{convert|14|inch|abbr=on|1}}
- {{convert|16|inch|abbr=on|1}}
- {{convert|18.5|inch|abbr=on|1}} (only for .300 Blackout)
- {{convert|20|inch|abbr=on|1}}
|width=
|height=
|diameter=
|cartridge=
|action=Gas-operated, rotating bolt, short piston drive
|velocity=
|effective range=
|max_range=
|feed=
- 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
| ref = {{cite web |url=http://www.msarinc.com/STGE4.html |title=Microtech Small Arms Research - STG-556 Sporting Rifle |website=www.msarinc.com |access-date=30 June 2022 |archive-url=https://web.archive.org/web/20100210190455/http://www.msarinc.com/STGE4.html |archive-date=10 February 2010 |url-status=usurped}}{{cite web |url=http://www.msarinc.com/downloads/stg556brochure.pdf |title=Archived copy |website=www.msarinc.com |access-date=30 June 2022 |archive-url=https://web.archive.org/web/20081209121742/http://www.msarinc.com/downloads/stg556brochure.pdf |archive-date=9 December 2008 |url-status=usurped}}{{cite web |url=http://msarinc.com/stg-556.html |title=Msar {{pipe}} STG-556 |website=msarinc.com |access-date=30 June 2022 |archive-url=https://web.archive.org/web/20110206063429/http://msarinc.com/stg-556.html |archive-date=6 February 2011 |url-status=usurped}}{{Cite journal | last = Choat | first = Chris | title = Microtech's STG-556 An Exclusive First Look| journal = The Small Arms Review| volume = 11| issue = 6| pages = 43–50| date = March 2008 }}
}}
The STG-556 is a Steyr AUG clone formerly manufactured by Microtech Small Arms Research (MSAR).{{cite web | url=https://www.guns.com/news/msar-stg-556-bullpup-you-dont-know-but-recognize | title=MSAR STG-556: Bullpup You'll Recognize|archiveurl=https://web.archive.org/web/20230509142425/https://www.guns.com/news/msar-stg-556-bullpup-you-dont-know-but-recognize|archivedate=2023-05-09}} It was available in civilian and military/law enforcement (select-fire) variants.{{cite web | url=https://modernfirearms.net/en/civilian-rifles/u-s-a-civilian-rifles/msar-stg-556-rifle-eng/ | title=MSAR STG-556 rifle | date=27 October 2010 }}
History
It was introduced at the 2007 SHOT Show. The first few STG-556 rifles were chambered in .223 Caliber.
In July 2012, MSAR resurfaced with a new STG-556 rifle variant known as the STG-E4.{{cite web | url=https://www.thefirearmblog.com/blog/2012/07/23/microtech-small-arms-research-msar-stg-e4-rifle/ | title=Microtech Small Arms Research (MSAR) STG-E4 Rifle | date=23 July 2012 }}
MSAR closed down permanently on March 20, 2015.{{cite web | url=https://www.thefirearmblog.com/blog/2015/03/23/microtech-small-arms-research-closes-its-doors/ | title=Microtech Small Arms Research Closes Its Doors - | date=23 March 2015 }} 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.
Design
The STG-556's design was based on the original Steyr AUG since the patents expired at the time. The frame was made on 7075 T6 aircraft-grade aluminum{{cite web | url=https://www.shootingtimes.com/editorial/longgun_reviews_st_microtechstg_200806/99253 | title=Microtech STG-556 | date=23 September 2010 }} and made from cast, unlike the TPD AXR as it was made through forging.{{cite web | url=https://defensereview.com/msar-stg-556-bullpup-rifle-4179-stanag-and-translucent-polymer-ar-magazine/ | title=MSAR STG-556 Bullpup Rifle (4179 STANAG) and Translucent Polymer AR Magazine }} It was available in black, tan and green finish.
It features a bolt release as seen on the M16 rifle and a forward assist. 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.{{cite web | url=https://www.athlonoutdoors.com/article/msar-stg-556-gebirgsjager/ | title=MSAR STG-556 Gebirgsjäger | date=14 September 2009 }} The gas regulator positions consist of "S", which is the normal setting and allows large amounts of gas to escape from the rifle.{{cite web | url=https://www.thefreelibrary.com/STG-556%3A+American+Combat+Bullpup%3A+if+you+missed+the+chance+to+buy+an...-a0196382591 | title=STG-556: American Combat Bullpup: If you missed the chance to buy an AUG back in the '80s, here's your chance to buy a U.S.-made version with some interesting improvements. - Free Online Library }} "H" diverts more gas into the rifle to allow the STG-556 to be fired in adverse conditions or extreme foulings. "GR" diverts gas into the system to fire blanks in order to launch rifle grenades.
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. Various accessories can be attached on the rail.{{cite web | url=https://www.tactical-life.com/firearms/msar-stg-556/ | title=Msar STG-556 | date=May 2008 }}
The STG-556 uses magazines similar to those used by the Steyr AUG (10/20/30/42),{{cite web | url=https://www.civiliantacticalweapons.com/wpctw/msar-mags/ | title=MSAR Magazines – Civilian Tactical Weapons }} being made up of “radel” (polyphenylsulfone). The rifles can also take 30-round STANAG and Magpul PMAG magazines. 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. All STG-556s without a forward-assist mechanism can take AUG magazines.
The barrel can accept a blank adapter or a suppressor.{{cite web | url=https://smallarmsreview.com/microtechs-stg-556-an-exclusive-first-look/ | title=MICROTEch's STG-556 AN EXCLUSIVE FIRST LOOK - Small Arms Review | date=5 March 2008 }}
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.{{cite web |url=http://msarinc.com/home.html |title=Microtech Small Arms Research - Home |website=msarinc.com |access-date=30 June 2022 |archive-url=https://web.archive.org/web/20090210211726/http://msarinc.com/home.html |archive-date=10 February 2009 |url-status=usurped}} It was previously sold with an OD green Currahee Knife and a MSAR Pelican 1700 case.
=STG-556 E4=
The STG-556 E4 was introduced in 2009. It can use AR-15 and M16 magazines. For any E4s that use .300 AAC Blackout, they can use the 18.5" barrel.{{cite web | url=https://www.guns.com/news/2012/07/02/msar-re-release-reopen-stg-556-update-stg-msar-returns-with-new-stg-e4-aug-style-riflese4-steyr-aug-clone | title=MSAR Returns with New STG-E4 AUG-Style Rifles }}