The New SIG SAUER AG SG56X Assault Rifles
- Marco Damaso
- Sep 6
- 5 min read
Introduction
My experience with the SIG SG550 family dates back to 1990, when I received the newly fielded 5.6 mm Sturmgewehr 90 (Stgw 90) as the standard assault rifle of the Swiss Armed Forces. In 2002, I was responsible for the trials and development of the SG551 and SG552 rifles with the newly formed special forces. This program led to the creation of the SG552 Long Barrel (5.6 mm Stgw 04).
Later, at the request of the special forces, SAN Swiss Arms AG developed a new telescopic stock and an improved spring system to replace the problematic mechanism of the SG552. This resulted in the SG553 long barrel (5.6 mm Stgw 07).
Naturally, I was keenly interested when SIG SAUER AG presented the new SG56X family at the end of last year in Switzerland and later officially at IWA 2025. I was eager to handle and shoot one, to see how the evolution of this rifle family had progressed.
As the SG56X is now available for sale in Switzerland, I was able to gain some first impressions on the range from a military/combat weapon perspective, which I am happy to share.
SIG SAUER AG SG56X
The SG56X can best be described as a marriage between the SG55X and the MCX. Its receiver, bolt carrier, bolt, barrel, and gas system are nearly identical to those of the SG55X, while the lower receiver and handguard bear a strong resemblance to the MCX.
The following models are available:
SG560 – 5.56×45 mm with 20-inch barrel
SG561 – 5.56×45 mm with 14.5-inch barrel
SG563 Long Barrel – 5.56×45 mm with 12-inch barrel
SG563 – 5.56×45 mm with 9-inch barrel
SG563 R – 7.62×39 mm with 12-inch barrel
SG563 BK – .300 Blackout with 12-inch barrel
The 5.56×45 mm and 7.62×39 mm variants are available in Switzerland for CHF 4,550, while the .300 Blackout version is priced at CHF 4,750.
Some key new features of the SG56X are:
Free floating M-LOK handguard
Fully ambidextrous controls
45° safety (90° possible)
Compatibility with SG55x magazines and AR15 magazines
Buttstock interchangeability thanks to a vertical STANAG 4694 rail
MAK DRS AR15 trigger, adjustable 1-1.3 kg
4-position adjustable gas valve — normal, adverse/dirty, suppressor, and closed (depending on the model)
The weapon I used was an SG561 equipped with a 14.5-inch barrel and an empty weight of approximately 3.8 kg.
First impressions
I have to admit, my very first impression was one of disappointment. One aspect I especially appreciated with the SG55X family was its distinctive green color, which had almost become a trademark of the series. The SG56X, by contrast, is delivered in black. In an era where more and more military weapons are being fielded in brown or green finishes, this design choice feels underwhelming.
But let’s leave emotions aside and be objective. The SG55X lineage is immediately obvious when you take the rifle in your hands, combined with a distinct AR15/MCX feel in the strong hand. What stands out, however, is that the rifle feels heavily front-weighted—even more so than an SG551 with rail handguard.
Note: When testing a new assault rifle for the special forces in 2002, the SG551 with rail handguard was found to be excessively front-heavy. This shortcoming led to the development of the SG552 Long Barrel (5.6 mm Stgw 04).
On the range, the SG561 performed essentially the same as the older SG551 and was pleasant to shoot. Below are some specific observations.
Controls
The controls (safety, magazine release, and bolt release) are ambidextrous, well positioned, and easy to operate during standard rifle handling such as loading, unloading, and clearing stoppages.
However, the magazine and bolt releases are relatively large and mostly unprotected. This makes them prone to unintentional activation during military patrolling or combat situations.
The bolt release functions differently on each side: on the left, it must be pushed down, while on the right, it must be pushed up to lock the bolt open. If the right-side bolt release is pushed up before pulling the bolt to the rear, the bolt locks in place and cannot be retracted.
The magazine release also shows inconsistency: the right-side release is protected and requires deliberate pressure, but the left-side release is completely unprotected, large, and extremely light to activate.
Note: The SIG MCX VIRTUS and SPEAR LT are in service with Tier 1 and Tier 2 special forces units in the USA, UK, and Israel. Compared to these, the controls of the SG55X are larger and less protected, reinforcing the concern about unintentional activation.
I am also not a fan of the 45° safety selector on AR15-type weapons. It worked reasonably well with the SG55X series because the distance between the lever and the “V” of the hand is longer than on AR15-type rifles (although it could not be engaged with the buttstock shouldered). On AR15 platforms, however, engaging the safety at 45° without overshooting into the full-automatic position is very difficult under stress.
Operational Impact: While the ambidextrous layout supports intuitive handling, the oversized and unprotected controls increase the risk of unintended activation in combat. The 45° safety selector further increases the likelihood of misoperation under stress, reducing both safety and reliability in rapid transitions.
Handguard
The free-floating M-LOK handguard of the SG56X has a similarly large profile to that of the SIG MCX Virtus. Unfortunately, due to the barrel and gas system design, it could not adopt the slimmer profile of the newer SIG MCX SPEAR LT.
Unlike the MCX (or the SG55X series), the handguard of the SG56X is fixed to a clamping block with screws and cannot be removed easily for cleaning. In addition, the handguard heats up extremely quickly during sustained fire, making it impossible to hold with bare hands. This is most likely due to the clamping block being fixed directly to the barrel, which causes heat to dissipate rapidly into the handguard.
Operational Impact: The fixed attachment complicates maintenance and field stripping, while the rapid heat transfer severely limits handling during sustained fire unless gloves or additional rail covers are used. This reduces both ergonomics and combat endurance.
Conclusion
The SG 56X represents SIG SAUER AG’s effort to modernize the proven SG55X lineage by incorporating design features from the AR15/MCX platforms. It retains many of the mechanical strengths of the SG55X while introducing modularity and compatibility with AR15 components, such as triggers and magazines. Several readers had already mentioned the new SG56X rifle in post comments, highlighting interest in SIG SAUER AG’s latest development made in Switzerland.
On the positive side, the SG 56X offers logistical flexibility, modern ambidextrous controls, and solid shooting characteristics that closely mirror the SG551. The compatibility with AR15 triggers and magazines provides adaptability across different operational contexts, while the adjustable gas system adds versatility for suppressed and adverse conditions.
However, several shortcomings limit its appeal as a front-line combat weapon. The rifle is noticeably front-heavy, even more than the SG551 with a rail handguard, reducing handling agility and increasing fatigue. The handguard design complicates cleaning and heats up excessively during sustained fire, diminishing ergonomics without protective gear. The oversized and unprotected controls raise the risk of unintentional activation, and the 45° safety selector introduces operational risks under stress. Finally, the factory trigger is too light for combat use, requiring replacement for military and law enforcement applications.
Overall, the SG56X is a capable and modern rifle that blends Swiss engineering with AR15/MCX features, but in its current configuration it appears better suited for sporting use than for combat deployment. The rifle requires serious modifications to become a competitive military or law enforcement weapon.
For now, I would clearly prefer the tried and trusted SG551.
Comments