This year I've had now three conversations/debate discussions as related to the design intent and testing measure of the Swiss Arms/Sig Sauer 55X series carbine and rifle as related to the latest variant of the line, the US market variant '556'.
Below are documents that should assuage anyone's thoughts, ideas, or doubts that the 55X series is not only as reliable as the US base Stoner designed M16/M4 (5.56) and AR-15 (.223) but is in fact far more durable and reliable as related to functional design, action, and assembly as components and firing assemblies.
Note that the US market variant '556' is _functionally_ exact same as the Swiss Arms/Sig Sauer 551-SP 'Sporterized' international market variant which is semi-automatic only rather than being select fire. The 'SP' model was developed for sale amongst the Canadian civilian market. Otherwise the 55X series up to the 556 has been an NFA Class III type firearm with select fire type fully automatic firing capable action as for application by military and law enforcement exclusively.
Outside of Canada prior, and now the US, it generally has not been available for sale to civilian markets. Unlike that of the AR-15 in specific. This is one of many reasons why the aftermarket for the 55X series is not as mature even as the firearm series has been around since 1980. Further the Clinton Administration passed bans against import of foreign military-style weapons without regard to their action type[/u] either as complete assembled rifles and as parts which prevented the 551-SP in specific from being imported. That ban continues to current.
That is why Sig Sauer, formerly Sig Arms of North America, developed the 556 variant. The lower/receiver is US made and the barrels are Swiss blanks unfinished that are mated to the upper as in finished condition here in the US in NH. In doing these two steps the rifle then becomes serialized in America, rather than Switzerland, and thus meets and beats the Federal law requirements becoming an 'American made' and NFA compliant as semi-automatic only carbine/rifle, as opposed to 'assault weapon'.
Somewhat complicated but not really if you understand current firearm laws and regulations. It is what it is and with the US military up to re-compete toward a new base carbine and rifle system in to the current and near future this was the no-brainer time for Swiss Arms/Sig Sauer to make this step. We civilian customers have benefit only now due to that timing as the opportunity was non-existant in years and decades prior.
Many people are completely unfamiliar with the 55X series as outside of Canada it has largely been an unknown commodity amongst North America through out it's _thirty year_ history as a largely non-commercial military arm.
By that unfamiliarity in addition to it's being a more than natural competitor to the dyed in the wool amongst Americans M16/M4/AR-15 rifle/carbine system some folks have blown off the 556 in specific as being 'garbage' or for lack of understanding how the system functions and the basically minor differences between it and the rest of the 55X series.
The most notable _functional_ difference between the 556 and the rest of the 55X series is in it's magazine well, the magazine it uses, and the magazine release.
The 556 is designed to accept and support STANAG type M16/AR15 magazines. If the magazine will run in your AR then it will run in the 556. Period. And as based on the 55X series' internal design which is much less complicated then that of the Stoner design those same mags will very likely run _better_ and more reliably in the 556, as well magazines you have lying around that do not run reliably in your AR will likely run fine with no problems in the 556 (!). Why this is will become quite obvious upon review of the Armorers Manual provided below which details the firearms action and/or direct inspection of a 556 variant.
The items below should help most anyone much better understand what the Swiss Arms/Sig Sauer 55X series is and in specific what the NA market Sig Sauer 556 has to offer, which is now available in multiple carbine variants as well as a factory short-barreled rifle (SBR) to compete against the Colt M4 as well in stockless pistol format and with a 24" long barrel rifle called the 'DMR' (Designated Marksman Rifle) that has been in development also for the NA market as based on a prior 55X variant called the '550 Sniper'.
The full document including results can be read at; SIG 550 / 551 Technical Data and Test DocumentationSIG Assault Rifles - SG 550 / 551
Technical Data and Test Documentation
Both weapon models. the SIG assault rifle SG 550 and the short-version SG 551, have been submited to the full range of endurance tests, verification tests and quality inspections described in this:
Technical Data and Test Document
SG 550 & SG 551
I. Endurance Trials
1. Barrel life expectancy: Test procedure
1.1. Firing sequence
1.2. Inspection and measurement
2. Weapon service life (guarantees)
2.1. Service life of individual components
2.2. Extended service life / Functional safety
II. Verification Tests
1. Rain trials
- Verification of accuracy
2. Sand and dust trials
2.1. Stationary sand and dust trials
2.2. Dynamic sand and dust trials
2.3. Sand drag trials
2.4. Mud trials
2.5. Testing under extreme temperature conditions
2.5.1. High temperature testing
2.5.2. Low temperature testing
2.5.3. Icing up tests
- Procedure, test no. 1
- Procedure, test no. 2
2.5.4. Cold tests, Jungfrau Joch
2.6. Functional reliability of unlubricated weapons
- Measurement of cyclic rate
2.7. Plastic magazines: Drop tests
III. Quality Inspections / Acceptance Criteria
1. Quality Assurance
1.1. Quality assurance programme
- Execution, surface and heat treatment
- Functions testing
- Dimensional testing
- Overpressure proof firing
- Zeroing the weapons
1.2. Accuracy trials with various makes of ammunition
IV. Interchangeability of components and sub-assemblies
SIG 550 and 551 Armourers Instructions
Note: I d/l this for archival purposes _and_ printed off a hard copy to file.
Do not print this unless you do not mind buring through a lot of paper. As well know to _remember_ to select reverse printing amongst your defaults (!). I learned this the hard way.
Swiss Army SW90 (550/551) Maintenance Manual
Note: If you do not read Swiss, do not bother to click. I provided this more for archival purposes than anything.
Sig 556 'SWAT' model (full rail front end) Field Strip
YouTube - Sig 556 Swat Field Strip
Images of Swiss _citizens_ carrying government military issue SG550 (rifle) openly as they go about their regular civilian area day, which is normal in Switzerland as per their laws and social views as related to arms, security, and 'home land defense' in general.
Very much different than America, American view toward arms at large, and our own laws & government.
Credits: Tim Orrock - Swiss Stuff pictures by Tim_Orrock - Photobucket
Additional reading regarding Swiss firearm laws:
* Gun politics in Switzerland - Wikipedia, the free encyclopedia
* BBC News | EUROPE | Switzerland and the gun
* Guns, Crime, and the Swiss - by Stephen P. Halbrook
* US vs. Switzerland Gun Laws
* Gun Control: Myths and Realities | David Lampo | Cato Institute: Daily Commentary
Series 55X including; 550, 551, 552, and 553
* SIG SG 550 - Wikipedia, the free encyclopedia
* The STG.90 Page
* Modern Firearms - SIG SG-550 SG-551 SG-552 Stgw.90 Assault Rifles
* SIG SG 550/551 (Stgw 90)
* SIG SG550, SG551 (Stgw 90) and SG552 Commando 5.56 mm assault rifles (Switzerland) - Jane's Infantry Weapons
* The SIG 550 a New Assault Rifle for the Swiss Army
* SIG SG-550-1 Sniper Rifle
* Disassembly Of A Swiss Army Stgw90 Aka SIG 550 Assault Rifle - Video
* YouTube - 300meter sniper by swiss (Chinese) recruit
Series 556 including; Classic, SWAT, Classic SWAT, SCM (restricted/AWB states model), ER, and Pistol
* Products & Services
* Products & Services
* Modern Firearms - civilan guns for self-defense, training and hunting - SIG 556
* GUNS Magazine May 2008 Feature
* SIG's 556 SWAT
* SIG 556 SWAT Gas-Piston-Driven Tactical Rifle/Carbine/Subcarbine
* Tactical-Life.com Sig Sauer SIG 556 5.56mm
* Sig 556 SWAT Review – Bill from Niles Michigan
* SIG 556 :: Index
* YouTube - sig 556 ('Michael Bane Review')
* YouTube - SIG 556 Gas System ('SIG 556 Gas System')
* YouTube - SIG 556 & AK47 Cousins ('SIG 556 & AK47 Internals Comparison')
"The Swiss are well armed and enjoy great freedom." - Machiavelli, 1532