Sig Sauer SIG516: The Ultimate AR-15 Style Rifle for Reliability and Performance

Author: Eric Sof

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The Sig Sauer SIG516 is a reliable and performance-driven semi-automatic rifle based on the AR-15 platform and chambered in 5.56x45mm NATO. It was introduced to the market in 2010, gaining popularity among shooters worldwide. Designed and manufactured by the renowned Swiss company SIG Sauer, the SIG516 has incorporated numerous improvements to enhance its accuracy, reliability, and overall performance compared to the AR-15 platform. The SIG516 was discontinued in 2019, and a variant chambered in 7.62x51mm NATO designated as the SIG716i remains in production.

Introduction

The AR-15 platform is one of the most popular worldwide, with many manufacturers creating models based on these rifles. Despite their popularity, quality, and widespread use, they have flaws. The Swiss company SIG Sauer has developed a solution to address these shortcomings.

American models are known for their excellent ergonomic design, compact size, relatively lightweight, and good firing accuracy. However, one potential issue with these models is that the powder gases acting on the upper front part of the bolt carrier can cause combustion products to enter the interior of the rifle barrel during firing, potentially damaging the mechanism, particularly the locking cams on the bolt. In 2010, SIG Sauer’s designers completed a new project based on the American AR-15 platform, but with an improved automatic mechanism that addresses this issue.

Sig 516 rifle with two magazines
Sig516 rifle with two magazines (Photo: XY)

It is also worth mentioning that in the basic layout, the SIG516 heavily resembles the HK416.

Design

The SIG516 automatic rifle is designed to use NATO caliber 5.56x45mm ammunition and operates using a short-stroke piston above the barrel, similar to the German HK416 and HK G36 systems. The rifle uses a rotary bolt design based on the AR-15 platform for locking. A unique feature of the SIG516 is the transmission lever behind the piston, which rests on the bolt carrier and transmits the movement of the piston to the mechanism during operation.

This design prevents the entry of gases and particles into the interior of the rifle, improving its reliability, safety, maintenance, and service life. The SIG516 also has a gas flow regulator that allows it to function reliably in all weather and terrain conditions. The regulator has three positions that can be manually selected and are indicated by different sizes and color dots. A small white dot indicates normal gas flow, a large white dot indicates increased flow for extreme temperatures or dirty conditions, and a red dot indicates flow adjustment for use with a suppressor.

SIG Sauer 516 rifle chambered in 5.56x45mm
SIG Sauer 516 rifle (Photo: XY)

Other design elements of the SIG516 are based on the AR-15 platform, primarily targeting the American market due to the ease of training officials and civilians in the tactical use of these rifles. The stock of the SIG516 is telescopic and made of composite materials, with the ability to adjust to six lengths. The adjustment is made by pressing a lever on the bottom and sliding the butt in or out. The rear end has a rubber shock absorber, and an ergonomically shaped cheekpiece made of composite materials and adjustable in height is also available. The straight-line configuration of the SIG516 improves its accuracy when firing.

The receiver’s cover on the SIG516 rifle has a handle for locking the bolt, which is similar to the AR-15 platform and does not move during firing. There is also a forward assist located below and on the right side of the receiver, which allows the bolt to be pushed into the locked position in case of incomplete locking of the bullet. The receiver is made of aluminum alloy and consists of an upper and lower part connected by two transverse pins.

The pistol grip is based on American designs, with the basic controls arranged identically to the AR-15 platform and easily accessible. The rifle’s firing mode can be changed by adjusting the fire selector, which also acts as a trigger guard and allows for single, burst, and in some models, three-round burst firing. The trigger has an optimally sized bumper that does not interfere with handling even when wearing gloves, and a pressure force of 1.5 kg is sufficient for release. The shell ejector is located on the right side of the receiver and is protected by a cover that lowers automatically when the bolt is engaged, following the example of American models.

A metal deflector on the rear side of the opening protects the shooter’s face from the impact of hot shells. When the last bullet in the magazine has been fired, the bolt remains in the rear position. A well-profiled bolt hold-open is located above the magazine well, and pressing it allows the bolt to return to the front position, so it is not necessary to lock the bolt handle after inserting a new magazine. The magazines have a capacity of 30 bullets arranged in two rows, and the button for releasing the magazine is located above the well and is easily accessible.

The SIG516 rifle has four Picatinny rails along the weapon’s upper and lower sides, which are supplied as part of the standard package and numbered in white to help the shooter easily remember where they have mounted additional tactical equipment. There are also folding mechanical sights on the upper side of the rifle.

The barrel of the SIG516 is made of cold-forged steel and is chrome-plated and fluted with a twist pitch of 1:178 mm (1:7 in). It is also equipped with a flame arrestor with longitudinal slots and varies in length depending on the model.

Variants

SIG716

The SIG716 is a battle rifle variant that builds upon the same design as the SIG516 but is chambered for the larger 7.62x51mm NATO round and uses SR-25 pattern magazines.

SIG716 G2

The SIG716 G2 (Generation 2) variant features a short-stroke pushrod gas system, which reduces carbon fouling, excess heat, and unburned powder in action, resulting in improved reliability and function. The SIG716 G2 Patrol model is chambered in 7.62x51mm NATO, while the G2 DMR model is chambered in 6.5mm Creedmoor. This wide range of caliber options makes the SIG716 G2 suitable for various shooting situations and preferences.

SIG716i

The SIG716i (impingement) variant of the SIG716 features a direct impingement gas system instead of the short-stroke pushrod gas system found on other models. This operating system has helped Sig Sauer lower the cost of manufacturing and increase sales of the SIG716i while reducing the rifle’s weight.

Indian army soldier from White Knight Corps armed with a Sig 716i
Indian army soldier from White Knight Corps armed with a Sig716i (Photo: Wiki)

Chambered in 7.62x51mm NATO, the 716i has been recognized as the best AR-10 rifle of 2020 by readers in Ballistic magazine. Sig Sauer has discontinued the SIG716 and SIG716 G2 models, as they are no longer displayed on the company’s webshop. They continue to sell magazines and spare parts for these models in their online store.

Users

In 2018, a batch of SIG516 CQB rifles was delivered to the Special Anti-Terrorist Unit (SAJ) of the Ministry of Interior of Serbia and the specialist units of the Gendarmerie of Serbia, equipped with B5 Systems Bravo Stock telescopic stocks, Magpul PMAG 30 AR/M4 M2 MOE Window magazines with a capacity of 30 bullets, and Aimpoint PRO Red Dot sights with rubber protection. The elite police units, who have been using Colt M4 rifles with a similar design for many years, have given very positive feedback on the SIG516 rifles.

Suppressed SIG 516 CQB
Suppressed SIG516 CQB (Photo: XY)

by country

  • Canada: Used by Canadian Special Operations Forces Command.
  • Egypt: Used by Navy El-Sa’ka Forces.
  • Georgia: In use with the Georgian MIA and MOD special forces
  • Hong Kong: Used by the Hong Kong Police Force, including the Special Duties Unit and the Counter Terrorism Response Unit.
  • India: Order placed for 72,400 units of SIG716i model. In December 2019, SIG delivered the first lot of 10,000 rifles to the Indian Army’s NorthArmy’smmand. SIG Sauer confirmed an additional order for 72,000 rifles in July 2020. The order for the second batch of 72,000 assault rifles would be coming after the first batch has been delivered. Sig Sauer also confirmed that delivery of the first order has already been completed.
  • Indonesia: Used by the Mobile Brigade of the Indonesian National Police, SIG716 G2 is used by the Indonesian National Armed Forces special forces unit.
  • Mexico: Transitioning into the general service rifle of the Naval Infantry Force.
  • Serbia: Used by SAJ (Counter-Terrorist Unit) of Serbian Police and Gendarmerie of Serbia
  • Switzerland: Used by the Mobilen Einsatzpolizei of the Aargau Police.
  • Turkey: Used by Police Special Operation Department and Police Counter Attack Teams
  • United Kingdom: Used by Metropolitan Police Counter Terrorist Specialist Firearms Officers (CTSFO), Surrey Police, and West Midlands Police
  • United States: Used by Florida Highway Patrol when purchased in 2019, Delaware State Police when purchased in 2012, and Cincinnati Police Department SWAT, as well as the Anderson County, South Carolina Sheriff’s Office SWAT. San Diego Police Department SWAT, in which the rifles will replace out aging Vietnam-era M16s.

Technical specifications

Country of origin:Germany / Switzerland
Manufacturer:SIG Sauer
Caliber:5.56×45mm NATO (SIG516)
7.62×39mm (SIG516)
7.62×51mm NATO (SIG716)
6.5mm Creedmoor (SIG716)
Weight (empty):7.3 pounds (SIG516)
Action:Short-stroke piston, rotating bolt
Length:36.7 in (extended)
33.0 in (collapsed)
Barrel length:16-inch (410 mm)
Muzzle velocity:
Magazine capacity:30 rounds
Sights:Iron sights or Picatinny rail for various optics
Range of effective fire:500 m
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