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SIG SIG551-A1 Review

SIG SIG551-A1 Review
The SIG551-A1 is a tough, reliable and accurate 5.56x45 carbine, although Fortier found it a bit sluggish to handle due to the weight.

While seen by few and shot by even fewer, the commercial semi-auto version of the SG550 rifle stimulated a great deal of interest among American collectors. Imported in very small numbers, specimens ran upwards of $7,000 when offered for sale. Many waxed eloquent regarding its build quality and accuracy. Some claimed the military Sturmgewehr 90 it was derived from was the finest assault rifle fielded. Collectors champed at the bit to get their hands on one.

When SIG introduced its SIG556 rifle, many purists turned their noses up at it. They didn't want a version molested to the point of accepting AR mags. No, only a 550 pattern rifle would do. Well, after years of waiting SIG Sauer has finally responded with the introduction of its SIG551-A1.

SIG first began development of 5.56x45 assault rifles in the late 1960s. The SG541 was initially adopted by the Swiss Army in 1983, but funds were diverted for the purchase of armored vehicles instead. When funds became available the SG541 had evolved into the SG550, and this improved model was adopted as the Sturmgewehr Model 90. Developed as a replacement for the obese but accurate 7.5x55 Stgw. 57, the Stgw. 90 was a much more practical design. A lighter and handier gas-operated assault rifle, it sported synthetic furniture and a folding stock.

In place of the odd blowback action of its previous design, SIG developed a gas-operated system. The heart of this is a rotating bolt and carrier assembly pirated directly from Kalashnikov's Avtomat series. Unlike the Russian design, though, the SIG's gas system is adjustable to allow an operator to compensate for a dirty weapon.

Magazines rocked in like an AKs, and the controls were similar. However an improved safety was added, along with a bolt release. The 5.56x45 SG550/Stgw. 90 earned a reputation for its build quality, accuracy and reliability.

The new SIG551-A1 looks like a 550 series rifle, but it is not an exact copy. Like the original it sports ambidextrous safety levers, paddle magazine release, synthetic furniture and a side-folding stock. The bolt handle is on the right side, and there is a rubber seal through which it passes to help keep debris out of the action.

In addition, the trigger guard may be rotated out of the way for cold weather use with mittens. A MIL STD 1913 rail runs along the top of the upper, facilitating easy mounting of optics. Sights consist of an overly complex diopter rear sight adjustable to 300 meters and a protected post front sight.

Feed is from flimsy-feeling translucent 20- and 30-round magazines that are designed to clip together. The 30-round design weighs 3.5 ounces empty.

The barrel is 16 inches long, sports a 1:7 inch twist and is fitted with a flash suppressor. Putting a tape to it rather than going by the company's literature I found it to be 36.5 inches long with the stock extended and 28.5 inches with the stock folded. SIG Sauer claims this model to weigh seven pounds without magazine, but my review sample tipped the scales at a much heavier 7.9 pounds.

In years past I lived a relatively short drive from SIGarms Academy and trained there regularly. Due to this I had frequent opportunities to train with and test fire selective fire 550 series rifles and carbines. I also had the chance to compare them head to head with a variety of competing designs.

Frankly, after playing with one I never understood the hoopla concerning this series of rifles. Interesting due to its rarity? Yes. Accurate and reliable? Yes. A significant improvement over a rack grade 5.45x39 AK-74M regarding reliability, durability, range, penetration, terminal performance, exterior ballistics or hit probability? Not hardly.

So I was interested to see how the new SIG551-A1 would stack up. Out of the box it looked very good. Build quality appeared first rate with nice looking machining and a handsome finish.


The action operated smoothly, but the safety was a bit stiff, which is pretty typical for a 550 series rifle. I found the trigger mushy but certainly usable.

Magazines inserted and locked into place smoothly without fuss. Balance point is right around the front pivot pin. With a loaded weight of around nine pounds, this model is a bit heavier than I would prefer.

Accuracy of the SIG551-A1 was quite good when put to work from the bench. Mated to a 1-4X scope the SIG delivered consistent groups at 100 yards. The SIG 551-A1 performed especially well when teamed with match-grade ammunition. Firing from the prone position gave consistent hits on a LaRue sniper target at 300 yards.

Running the 551-A1 through drills inside 50 yards revealed it to be a bit sluggish due to its weight. Controllability was good rifle for a rifle with a flash suppressor, but it was nothing to write home about. Reliability was flawless, even with Wolf steel-case ammunition.


SIG Sauer's new SIG551-A1 is both extremely robust and reliable. Its best features are how simple, tough and accurate it is. Basically it has all the virtues of Kalashnikov's Avtomat with a bit of refinement.

However, this isn't 1984. If compared to more modern designs such as FNH's SCAR, Bushmaster's ACR or Robinson Armament's XCR, it looks dated. Neither is it inexpensive with an suggested retail of $1,986. Still, if you have the AR-15 blahs and are looking for a very tough and reliable 5.56x45 rifle, SIG Sauer's SIG551-A1 is one to consider.

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