Sig Sauer 556

With a history dating back to just after the end of World War II as the standard military platform used by the former Soviet Union, the AK-47 served as a symbol of communist aggression behind the Iron Curtain. Considered one of the earliest assault rifles, the AK, and its variants, is chambered in 7.62x39 mm, and while it has been accused of being ugly, it is extremely reliable.

There are many countries where the AK and its chambering is still in use, though some have relegated  both to reserve status, preferring to use standard NATO rifle and cartridge designations. There are, however, untold amounts of military surplus 7.62x39 mm ammunition, making it one of the most commonly available rounds in the world. Because of this manufacturers have entered into this market and developed rifles in this chambering, such as the SIG Sauer 556R.

The 556R is built on the same rotary bolt, two-position adjustable-gas piston system as the 5.56x45 mm versions that have been available since shortly after SIG built its New Hampshire plant. The two-position gas valve allows the gun to be adjusted to continue running when dirty or being used in adverse conditions. This system also allows the stock to be folded toward the ejection port, without blocking the port during firing, to provide a more compact rifle platform for use in tight spaces, while also offering a full-length stock that can be quickly flipped into place for more support.

The forearm, butt stock and pistol grip of the 556R are made of black polymer, while the metal components are covered in a matte-black finish that is evenly applied, providing coverage and protection for all parts. Some of the well-thought-out extras include an ambidextrous safety, a spring-loaded trigger guard for accommodating gloved fingers and storage in the pistol grip.

Disassembly is simple, though it does include numerous steps. First, remove the AK-style magazine and ensure the firearm is unloaded. Then press the rear take-down pin from the left side and pull it to the right until it stops before pressing the pivot pin in the same way. From here the top receiver will lift off of the trigger housing. Depress the charging handle catch and remove the charging handle. Use the charging handle to push the bolt carrier to the rear and remove it from the receiver. Rotate the bolt head counterclockwise until the lug clears the cam and separate the units. Remove the firing pin from the bolt head by depressing the pin and knocking out the stud with a punch (be careful not to let the firing pin shoot out under pressure from the spring).

The dual-piece forearm is removed by pulling back and down on the lower piece and lifting the upper away from the gas block. Remove the gas valve by depressing the pin on the left side and rotating the unit to the left and removing, which allows the operating rod assembly to come out. Then, depress the pin on the left again and rotate the gas tube 90 degrees and lift.  Anything further should be done by a qualified gunsmith. Reassembly is done in reverse.

Once back together, SIG recommends a function test by, once again, ensuring the rifle is unloaded and pulling the reciprocating charging handle to the rear and allowing it to go back into battery. Put the safety lever on “safe” and pull the trigger. The hammer should not drop. Turn the lever to “fire” and pull the trigger. The hammer should fall. Finally, hold the trigger to the rear and cycle the charging handle. The hammer should not drop when the gun returns to battery, but should when the trigger is released and pressed.

Range work began with the included SIG Sauer red-dot optic. The red dot was easy to mount and sight in, and exhibited decent self-defense accuracy. At ranges between 25 and 100 yards, center mass hits were obtained during drills, and groups shrank considerably when using supported shooting positions, such as kneeling, prone and barrier. However, since the optic is only 1X, I would have preferred iron sights for durability and to eliminate the need for a battery. SIG Sauer offers aftermarket iron sights, as do some other companies, but they don’t come standard.

Its unloaded weight of 7 pounds and mild 7.62x39 mm chambering, provided very little recoil and allowed fast follow-up shots during multiple target strings. Even when firing with the butt stock in its forward position recoil was manageable, though accuracy suffered greatly, and the rifle ran with zero problems throughout testing. The trigger, however, was of the typical battle type, with significant take up and a fairly heavy trigger pull at just over 7 pounds. The pistol grip was comfortable and fits most hands well, though smaller hands might have a problem reaching the safety mechanism, and the forearm was easy to hold and never became hot, regardless of the number of rounds fired.

For formal accuracy testing, I mounted a Night Force 2.5-10x24 NSX riflescope on quick-detach mounts and settled the gun into a Caldwell Fire Control rest with two Winchester loads and one Tula steel-case load. Accuracy was decent, but not spectacular in five-shot groups with the Winchester 123-grain soft point loads averaging 2.34 inches and the Winchester 123-grain FMJ averaging 2.5 inches. However, I noticed throughout the process that three-shot groups stayed right at the 1-inch mark, with the fourth and fifth shots adding significant spreading in the groups. In a couple of groups, it was the fifth round that increased the spread. The Tula 122-grain FMJ load fared similarly with multiple three-shot groups measuring just a little over an inch, while five-shot groups spread out into the 2 and 3 inch ranges. The Winchester soft points had multiple, three-shot groups that measured under an inch, and was determined as the best load during the testing procedures.

The 556R comes with a single 30-round magazine of the AK variety. It is made of polymer in Bulgaria, and was easy to work with throughout testing, securely fitting into the magazine well, with fast removal. The magazine was quite durable as it was dropped several times during testing, and showing no sign of breakage, and like the AK, the bolt doesn’t lock open on the magazine with the last round. Since most standard AK magazines should work with the 556R, only one metal magazine was tested, the lack of an additional magazine isn’t a huge problem, but it would be nice to have at least a second magazine come with the rifle.

Overall, the SIG Sauer 556R performed admirably, and is excellent for what it is intended—a better-made rifle for firing the 7.62x39 mm caliber round. It is a fighting and self-defense rifle, not a sub-m.o.a. precision rifle. It is fun to shoot, and would work well on large targets out to a few hundred yards, while excelling on fast-action, close-range targets, with what could arguably be the most plentiful round in the world.

Manufacturer: SIG Sauer; www.sigsauer.com
Caliber: 7.62x39 mm
Action: semi-auto, rotary bolt, two-position adjustable-gas piston
Receiver: aluminum
Barrel: 16”
Rifling: 1:9.5” RH twist
Magazine: single 30-round polymer
Sights: none; mini red-dot sight
Trigger: 7.15 lbs. 
Stock: polymer
Overall Length: 35.875”; folded 26”
Weight: 7 lbs. without magazine
Accessories: lock; 1” butt plate extension; hand guard rail kit for mounting accessories
Suggested Retail Price: $1332

Source : http://www.americanrifleman.org/articles/sig-sauer-556r-review