The SIG551-A1 Carbine
The Swiss are a shooting culture, and as much as we have recently enjoyed their milsurp K-31s, Switzerland’s modern tactical rifles are gaining traction in the shooting sports. The advanced designs generated by Switzerland’s indigenous firearms industry, Schweizerische Industrie Gesellschaft (SIG), in Neuhausen am Rheinfall, has insured Switzerland’s long standing reputation for finely crafted and exceedingly accurate arms. SIG’s new 551-A1 civilian model is an outstanding example.
In the 1950s, Switzerland fielded their radical looking Sturmgewehr 57 (StG 57), known also as the SIG 510 in commercial form, which replaced all of those lovely Schmidt-Rubins that have washed up on our milsurp shores. The StG 57 featured a retarded, roller-lock mechanism, based on an earlier Mauser design, which Heckler & Koch successfully incorporated into their MP5, P9, G3, HK91 and HK 93 models.
A few years later, SIG introduced the Model 530 series chambered for 5.56 NATO. While the model still retained the roller-locking bolt, the advanced stocking and outward profile of the SIG 530 family set the pattern carried on in the SIG551-A1 today.
The next SIG generations to make their debut were the SIG 540 (5.56 NATO) and SIG 543 (7.62 NATO) in the early 1970s. The significance of this development with regard to the current SIG551-A1 is the earlier roller locking system was replaced by a long-stroke, gas piston that activated a bolt carrier and a rotary locking bolt.
In principle, the new locking system resembled the familiar Kalashnikov design—and many have made that comparison—however, according to the recent research conducted by Gary P. Johnston and Thomas B. Nelson and documented in their excellent book, The World’s Assault Rifles, the SIG/AK system first appeared in the Czech ZK420-S rifle in 1942. The SIG system exhibits the refinement of the Czech system while the Kalashnikov system is a simplified version of the gas piston, bolt carrier design.
The SIG551 was introduced to military and law enforcement circles as an tactical carbine with a folding stock, shortened barrel and selective-fire control system, offering semi-automatic, 3-shot burst and full-automatic modes of fire. In fact, the excellent owner’s manual accompanying the 551-A1 is written as if the carbine was furnished with a selective-fire capability. The manual also contains the technical specifications for two, extremely compact versions of the 551-A1, featuring 10″ barrels and designed for special operations deployment.
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