Real Steel History
The SIG 556 is a member of the SIG 550 family manufactured by Swiss Arms AG (formerly SIG Arms AG) of Switzerland. The original 550 was developed as a replacement for the Stgw 57 (SIG 510) battle rifle. One of the requirements for the replacement was for the rifle was to be modular as the weapon family was to include several variants of the base design, including a carbine with a shorter barrel (SIG 551), A commando version with a shorter handguard and an even shorter barrel (SIG 552) and even sniper versions.
The SIG 556 is the commercialised variant of the 551 carbine, designed specifically for the American market. One thing that was different on the 556 compared to the other 550 models was the lower receiver, which has been designed to take standard M16 magazines. Other changes include an M4 telescoping buttstock, and Picatinny rails and simpler front and rear flip up sights. All other parts of the SIG 556 are compatibly modular with the rest of the SIG 550 family.
Airsoft Variant’s
Until recently the on SIG 556 option for an airsoft AEG, was to purchase and install a conversion kit for a SG 552. All that recently changed when King Arms released a licensed replica of the SIGARMS 556 rifle.
https://www.defconairsoft.co.uk/product/king-arms-sig-556-holo-full-metal-blowback-aeg/
On the initial launch King Arms released two versions of the SIG 556, which were:
- SIG 556 HOLO.
- SIG 556 HOLO DE (Dark Earth Colour).
So what’s in the box?
Previously when we have received models from King Arms we have not had chance to see the final packaged box. In this case we have been lucky enough to receive a retail box.
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As with previous AEG’s we have received from Kings Arms, inside the box the AEG has been packed in foam.
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The box contents include the SIG 556 AEG, Magazine and instruction manual as you would expect. Additionally King Arms have supplied parts to allow you to disable the blowback on the AEG and a speed loader. |
Initial Impressions
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Like other King Arms AEG’s we have reviewed, the SIG556 has a full metal receiver, this gives the gun a nice feel and weight.
Immediately you can see similarities to M4/M16 AEG’s However on closer inspection it is apparent while some things like the sliding stock and magazine catch, the receiver and handguard are quite different. |
The specifications of the SIG556 are:
- Full Metal receiver with nylon fiber handguard.
- 7mm Bearing Gear Box.
- Special designed Bolt Carrier Operating Mechanism which can be remove after modification.
- 330fps
- 135 Rds Magazine Included
- Weight: 2.85kg
- Length: 86-94cm
Receiver
As already mentioned the receiver full metal constructed from aluminum, with an anodized matt black finish on that looks amazing. We have taken the SIG556 to a couple of skirmishes none of the paint work rubbed away, where normally we would expect it to when the body is rubbing against webing.
The receiver includes a scope rail running accross the top, and to make the SIG556 holo a little more authentic King ARMS have fully licensed authentic SIGARMS markings on the left hand side under the rail.
The magazine catch and fire selector are again made of metal, and like the real 556the lower receiver has been designed to take standard NATO 5.56 magazines. This means that standard M4/M16 airsoft magazines should fit.
Barrel and Handguard
The outer barrel and flash hider and fake gas block all have dark gray finish. The outer barrel is one piece so there is no chance of any barrel wobble. The nylon fiber handguard is constructed in two pieces. Both the upper and lower half are extremely thick, and will survive any knocks they will get.
The handguard include two small side rails for attaching torches, lasers etc. On the bottom there is also a rail running almost the entire length of the lower handguard , this should enable you to use a vertical grip and possibly a RIS fitting M203.
The handguard lower half holds the battery, and will except a standard 8.4v mini battery. Unfortunately a 9.6v battery will not fit, however it would be fairly easy to modify the lower handguard to enable you to fit one.
Access to the battery is done by removing the front pivot pin on the receiver. The pin is a little tight at first however this does loosen after a while, however its remains tight enough that this will not fall out during a skirmish.
Sights
Both the front an rear sights are flip up, the front sights are adjustable for windage while the rear are adjustable for elevation.
While the sights are functional most people are going to opt for fitting either a scope or other form of optics.
Blowback
One of the features we have not mentioned so far is the inclusion of a blowback mechanism. We have already come across this feature on the Galil we reviewed. When enabled the blowback moves the charging handle back and forth.
The blowback works by positioning the blowback mechanism on top of the gearbox. The mechanism is mechanically connected to the top of the piston, via a modified V3 gearbox, therefore it is the backwards and forwards movement on the piston in operation which cycles the bolt.
This is one of these features you will either love or hate, I personally love it. You do feel the blowback in your shoulder, and the sound coming from the AEG is fantastic. However we can see the downside in that it does give your position away. Thankfully for those who hate this feature It can easily be disabled, and King Arms provide instructions on how to do this, these are easy to follow and it does not take very long.
Stock and Magazine
We have already mentioned that the SIG556 comes with a sliding stock. Made out of the nylon fiber with the end having a removable rubber butt pad on it, the stock has 6 positions. Unfortunately like most sliding stocks, there is a bit of wobble. This can be easily fixed, the solution we have used in the past is to pad out the stock pipe with electrical tape. However as this is a standard fit you can always fit another stock.
King Arms have chosen to include a 135 round replica of the SIG polymer magazine. The magazine includes the SIGARMS trades. As already mentioned the real SIG556 was designed to user standard M16 magazines, and the airsoft version is no different. We have heard reports of some magazines being tight however we have not had this problem with either Tokyo Marui or Classic Army magazines that we tested ths with.
Gearbox Inner Barrel and Hop
As already mentioned Inside the AEG, King Arms have fitted a version 3 gearbox. This is similar to the gearbox as used on the Galil however it does have a longer air nozzle. The gar box includes steel gears 7mm bearing brushes, ventilated piston head, brass cylinder, plastic cylinder head. The motor is unbranded and is accessed via the plat in the bottom of the pistol grip.
As already mentioned the SIG556 uses M4/M16 magazines, King Arms have therefore chosen to fit the AEG with a standard M4 metal hop unit. As the HOP unit sits too far forward King Arms have fitted a plastic spacer between the gearbox and Hop unit.
Fitted to the Hop unit is a standard bore brass inner barrel that is over 420mm in size, that over 57 mm more than a standard M4 carbine.
Performance
One area that surprised us was the FPS of this AEG, we tested this on the Madbull chronograph that Madbull Airsoft kindly donated to us. Initial results were 338-342 FPS.
Once we got the Hop set for optimal range the FPS lowered a little to 329 fps. Next we tested the rate of fire on a 8.4v battery and got a very respectable 820 rpm.
Once we had fed through a few hundred rounds range was better than my M4 carbine, and at 20 meters we were achieving groupings less than 10 cm’s apart.
Skirmishing with the AEG was a joy, the rifle was solid and. We forgot to take a sling with on the day we tested it, and the AEG was dropped once or twice. All we had to do was wipe the dirt away. When checked later there were no marks on this what so ever.
What was funny was looking a peoples reactions, many people were looking confused trying to work out what rifle this was before being told what it actually was. It certainly attracted a lot of attention. We hope to test this over a few more skirmishes to see how this continues to perform, and will update this review with further information.
Conclusion
This is a fantastic AEG, performance was spot on, and its a unique AEG on the skirmish field. The big advantage of utilising standard parts like Magazines, Stock, and Hop unit. And the version 3 gearbox can can take most upgrades that are available.
If you still want even more RIS space, King Arms now supply a aluminum RAS / handguard which should fulfil all of your needs. Or alternatively King Arms supply a model with this already fitted.
Another new model King Arms have released is the SIG556 shortly which is ideal for CQB. All the models have the blowback feature, which comes with the instructions and parts to disable this.
