Ruger SR-556c Semi-Auto 5.56x45mm Carbine


by Jeff Quinn

photography by Jeff Quinn & Boge Quinn

May 21st, 2010




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It has been a year since Ruger introduced their entry into the popular AR-15 market. Instead of jumping in with a stripped-down rifle assembled from parts bins as do many who build ARs, Ruger introduced a top-of-the-line rifle built with high quality parts. Featuring a very simple and reliable gas piston system with a four-position regulator, the Ruger SR-556 has been well-accepted in the marketplace, even though it is priced higher than the entry level ARs available from other builders. The SR-556 wears quality components that many shooters add anyway, such as a quad rail hand guard and folding sights, resulting in a rifle that is very accurate and ready to go to work right out of the box.

Since writing about the SR-556 last year, I have heard but two areas on complaint. The first is the price. The only way to lower the price and still make a profit is to cut material or labor costs. Using lower-priced components would certainly lower the cost to produce the rifle, as would having the rifle assembled in a foreign country with a depressed economy. Ruger builds their firearms entirely in the United States from American made parts, many of which are made in-house by Ruger employees, and importing the rifle is not an option. The materials used in the SR-556 are top notch, and Ruger chose to build a better rifle than the many entry level guns already on the market. There are many low priced AR-15 style rifles available, and they are all pretty good guns, but many are imported or use commonly available mass-produced parts. That is satisfactory if that is what you want, but the SR-556 is a cut above the common AR-15 rifle, and with the quality of components used and the care in assembly using American labor, it is still a good value for what you get. That addresses the price issue.

The second complaint that I have heard is that the SR-556 is too heavy. To me, that is not the case. Ruger uses a high quality hammer forged barrel with a semi-heavy profile in the SR-556, which attributes to the rifle’s fine accuracy. For me, accuracy is everything, and the muzzle-heavy balance of the SR-556 feels pretty good to me. However, Ruger chose to address this issue with the introduction of the Ruger SR-556c. The 556c still uses a barrel of the same diameter inside the quad rail hand guard (.850 inch), but the barrel is heavily fluted to reduce weight and promote faster cooling. Also, to reduce the weight a bit more and to reduce the overall length of the barrel, and thus the rifle, the flash suppressor is machined integrally with the barrel. The barrel has the same overall length as does the barrel of the SR-556, but by using an integral flash suppressor instead of a threaded-on flash suppressor, the overall length of the 556c is one and three-quarters inches less that that of the original SR-556. Fluting the barrel and shortening it shaves off about a half pound from the rifle’s barrel, dramatically changing the balance of the rifle. The 556c handles quicker, and the reduced length makes it a bit handier in tight quarters. Wearing the same six-position buttstock of the original SR-556, the SR-556c has an overall length of between thirty-one and thirty-four and three-eighths inches approximately, depending upon the position of the buttstock.

I covered the features of the original Ruger SR-556 in the review last year, so will just hit the high points here. The SR-556c still has all the features of the original such as the aforementioned four position gas regulator, chrome plated bolt carrier, and Troy Industries quad rail, covers, and folding battle sights. It also has a Hogue pistol grip and comes with three thirty-round Magpul magazines with feed lip covers, and a handy padded carry case.

I fired the new SR-556c using every type of 5.56x45mm and .223 Remington ammo that I had available for function testing, and also used several of the better quality brands for accuracy testing. I mounted a Leupold Mark 4 8.5 to 25 power riflescope for accuracy testing using an ArmaLite 30mm mount. All accuracy testing was done from a solid bench using a Target Shooting, Inc. Model 500 rifle rest. Being as this carbine is built for serious purposes, the trigger pull is pretty much standard AR, which is great for social work, but I prefer a lighter pull for benchrest target work. The trigger pull measured around six and three-quarters pounds on the test weapon. However, the Ruger still turned in a stellar performance, and I was surprised at the level of accuracy displayed by this rifle. I really should not have been, as it uses the same basic chrome-plated, hammer-forged barrel of the original SR-556, and I was using some ammunition that has proven to be very accurate in many other rifles. I was concerned that the Ruger’s 1-9 rifling twist would not stabilize the Buffalo Bore Sniper ammo with the long 77 grain Sierra bullet, but those concerns proved to be unfounded, at least out to the limits of my 100 yard rifle range. I will probably try the ammo out at longer range in a couple of weeks, but at 100 yards, the accuracy was superb, with no indications of instability at all. Range conditions were mild, with a slight breeze and an air temperature of seventy to seventy six degrees Fahrenheit at an elevation of approximately 541 feet above sea level. Accuracy and velocity results are listed in the chart below. Velocities are listed in feet-per-second (fps). Group sizes are the averages for three-shot groups at 100 yards. Bullet weights are listed in grains.

Ammunition Bullet Weight Velocity Group Size
Lake City SS109 62 2997 2.250"
Winchester USA FMJ 62 2832 1.250"
Winchester USA FMJ 55 2788 2.920"
Extreme Shock FHVL 62 2714 0.875"
Extreme Shock SRT 55 2432 1.000"
Black Hills HP 69 2674 0.500"
Wolf Gold HP 75 2478 1.320"
Buffalo Bore HP 77 2674 0.560"

I was well-pleased with the performance of the SR-556c. Functioning was flawless. I left the gas regulator set to position 2 for all testing. The rifle fed, fired, and ejected every round perfectly. Accuracy was good with every load tested, and superb with a couple of them.

The SR-556c is a welcome addition to Ruger’s line of semi-automatic rifles. It balances well, is very handy, and relatively lightweight at only seven pounds, ten ounces. However, all of the weight that was removed was removed from the front end of the weapon, and really makes it more “lively”, to use a shotgunner’s terminology. Retaining all of the great features of the original SR-556, the SR-556c is just a better-balanced, faster-handling carbine, and another fine choice for those looking for a top-tier AR-15 gas piston carbine.

For more information on Ruger products, go online to

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To order the SR-556c online, go to

Jeff Quinn


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Best accuracy performance was with Black Hills and Buffalo Bore ammunition.







Hogue pistol grip.





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Click pictures for a larger version.


Ruger SR-556c semi-auto carbine.



The SR-556c comes with a soft case, three thirty-round Magpul magazines, instructions, sight adjustment tool, pad lock, and rail covers.



Sight adjustment tool.



Barrel flutes can be seen through ventilated handguard.



Troy Industries folding battle sights.



Chrome-plated bolt carrier.



Four-position gas regulator.



Integrally-machined flash suppressor.