The SIG SG550 owes a lot to it’s predecessor- the SIG SG510. Not in terms of any design or mechanical legacy, but sheer necessity to break from it’s mold.
\nThe 510 was a fine piece of design, but that came at significant cost- it’s the most expensive Standard Issue Rifle fielded, and with it came a lot of export-minded drawbacks: it was not easy to maintain, it was heavy, and it was built for full-power rifle rounds.<\/p>\n
In the 1978, both major Swiss Arms companies (SIG and W+F Bern), set about building it’s replacer. SIG’s pattern – the SG541 – won out in 1981 and with minor alterations started production in 1983 as the SG550.
\nBy previous standards, the 550 is a heavily economised design. It sheds many intricacies found in previous rifles, but the two things that made it such a powerhouse:
\nThe first, a stamped steel receiver (capitalising on the techniques learned on the P220, cutting down production times significantly).
\nThe Second was a long-stroke gas piston whole form copied from the Soviet AK ( down to the locking recesses and bolt design).
\nThe Swiss Army formally adopted rifle, and a shortened carbine, as the STG90. The gun fires 5.6mmx45 GP90 (5.56mm NATO) rounds in semi, full-auto or 3 shot bursts, feeding from 10,20,30 round translucent box magazines (Beta systems do make a 100 round C-Mag drum, but they’re rare and unreliable).
\nIt’s capable of firing rifle grenades, comes standard with a bipod, and has diopter sights with inbuilt night setting. Over the last 25 years it has seen numerous additions to the platform, starting with the 550-1 Sniper, being joined by long barrel carbine iterations, the 552 “Commando” and 553 SOW, 553R (a sub-compact version chambered in 7.62×39), and most recently, a .300Blackout chambering soon to hit the European markets.<\/p>\n
The NIArms SG550 is effectively comprehensive. Of all the variations of the primary 550 family, this covers all but 2 of the models, (and the SIG-Sauer SG556 family branch,) on the market, spanning the entire service life of the system.<\/p>\n