Ruger SR-556C Review
Part 3 - External Features
January 1, 2011

Ruger SR-556C Review

The Ruger SR-556C rifle comes as shown above and includes Troy Industries Sights, Troy Industries Rail Covers and Magpul Magazines.  In this portion of the review, I'm going to remove these items to show the basic rifle and and then discuss them separately at the end of the review.  With these components removed, the configuration of the rifle for the photos in this part of the review is shown below.  Throughout this review, you can click on a photo and bring up a high resolution photo showing even more detail.

Figure 1
Ruger SR-556C Review

Upper and Lower Receivers

Two of the most critical components in any AR styled rifle are the upper and lower receivers.  Both receivers are machined from forged 7075-T6 aluminum and are Type III Hardcoat Anodized.  In general, this has become the standard for these components on your high end rifles.

Ruger decided to maintain a complete Mil-Spec lower receiver so that all interfaces are standardized which allows the lower receiver to mate up with the maximum number of aftermarket components.  When I checked Ruger's website today, it was also clear that they had an even greater vision.  Now they offer the option to purchase the full upper assemblies.  Since these assemblies mate up to a Mil-Spec lower, they can now compete with other manufacturers who sell upper assemblies also.

As you can see below, the lower receiver assembly is configured with the trigger assembly, bolt catch, safety, magazine catch, and takedown pins.  The lower receiver accepts all standard AR-15 magazines.

The trigger pull averaged to be 8.2 pounds after making 6 measurements.  I'm curious to see what it will be after more break-in during range testing because I consider this to be on the high side.  Granted this is not a sniper rifle, but I would prefer to see something in the 6 to 7 pound range.

Figure 2
Ruger SR-556C Review

Figure 3
Ruger SR-556C Review

The upper receiver assembly is a flat top and contains the charging handle, forward assist, case deflector, ejection port cover, and bolt carrier assembly.

Figure 4
Ruger SR-556C Review

The rail portion on the upper receiver is a Mil-Std 1913 Picatinny rail.

Figure 5
Ruger SR-556C Review

Quad Rail Handguard

The Quad Rail Handguard is manufactured by Troy Industries specifically for the Ruger SR-556 rifles.  These are machined from a billet of 7075-T6 aluminum and Type III Hardcoat Anodized just like the receivers.  On the bottom of the quad rail, you can see the manufacturers mark, part number and lot number for this quad rail.  The rails on this handguard are Mil-Std 1913 Picatinny rails.

Figure 6
Ruger SR-556C Review

The top rail has 22 slots and measures 9.13" in length.  This rail is shorter than the other three rails to allow for the long gas block which houses the piston system.  As you can see, the gas block also includes rail slots so this shorter length is of no consequence.

Figure 7 - Top of Rail
Ruger SR-556C Review 

The right, bottom and left rails all have 27 slots and measure 10.88" in length.  You can also see that every other rail slot is marked by side (T, R, B, L) and slot number.  The slot numbers start with 1 through 13 on the upper receiver and continue with 15 and go through 41 on the the sides and bottom of the quad rails.

Figure 8 - Right Side of Rail
Ruger SR-556C Review

Figure 9 - Bottom of Rail
Ruger SR-556C Review

Figure 10 - Left Side of Rail
Ruger SR-556C Review

The quad rail is pinned to the upper receiver using the three roll pins as shown below.  The upper two pins appear to secure the top of the rail by nesting in detents in the rear guide bush that passes from the upper receiver into the upper portion of the quad rail.  I have studied the parts diagram and I'm not sure how the lower roll pin works and I felt that removal of the handguard is too great of a task for me to do just for my curiosity of this pin.  I am impressed with how well this system works for keeping the quad rail secure to the upper receiver.  The actual surface finishes on the upper receiver and the quad rail matched nicely.

Figure 11
Ruger SR-556C Review

The quad rail is supported on the front end by the gas block as shown below.  I believe it is the combination of the pinning at the rear and this support at the front that gives this upper assembly a solid feel.

Figure 12
Ruger SR-556C Review

Gas Block, Flash Hider and Barrel

Since the front of this rifle is so short, it makes sense to cover the gas block, flash hider and barrel features with the same set of photos.  These steel components are Manganese Phosphate coated (which is to say they are Parkerized).  It is this manganese phosphating that gives these parts their dark-gray color.

The gas block measures 3.175" in length with the top rail portion being the longest part of the block.  The top front of the block has an arrow head made from 5 dots identifying the gas port setting (i.e. 2 in the photo below).

Figure 13 - Top
Ruger SR-556C Review

The gas block houses the gas piston and is held in place on the barrel by two solid pins.  Under the handguard, there is another ring on the gas block that circles the barrel at the rear portion of the block to give it more support.  During Part 4 (Disassembly and Internal Features) of this review, I will go into more detail on the gas piston system.  The exterior of the regulator (black knob) is marked with 0, 1, 2, 3, and an arrow.  The 0 setting causes the rifle to function in a single shot mode.  The 1, 2 and 3 represent gas port openings from smallest to largest.  The arrow is the position to use for removal of the regulator.  You can also see in the photo below the head of the regulator pin and the regulator detent clip.

Figure 14 - Right Side
Ruger SR-556C Review

On the bottom of the gas block is a hole to allow for staking the rear solid pin to prevent it from working loose.

Figure 15 - Bottom
Ruger SR-556C Review

Figure 16 - Left Side
Ruger SR-556C Review

One of the most significant features of the "C" model of the Ruger SR-556C rifle is the integrally machined flash hider into the end of the barrel.  This reduces the total length of the rifle by 1.75" (based on Ruger's specifications) but still maintains a 16.12" barrel length and the flash hider feature.  Not only does it reduce the length, it also reduces the weight at the front of the gun.  The SR-556C rifle is 0.54 pounds lighter than the standard SR-556FB model.  Based on some simple calculations, about half of this weight savings comes from shortening the total barrel plus flash hider combined length.

Figure 17
Ruger SR-556C Review

Figure 18
Ruger SR-556C Review

The photo below shows the integral flash hider on the Ruger SR-556C (top) along with the flash hider that comes standard on the other 5.56 NATO Ruger SR-556 rifles (bottom).  After studying both, it looks like Ruger has tweaked the flash hider profile on the SR-556C to a profile that is more readily machined.

Figure 19
Ruger SR-556C Review

The barrel plus flash hider extends past the gas block by 4.11", which seems very short.  The barrel diameter forward of the gas block measured at 0.625".  The barrel is cold hammer forged, made from Mil-Spec 41V45 steel, and is chrome lined.  All of these represent what you would find on any high end rifle barrel.  I want to explain the Mil-Spec 41V45 steel some more because there is a little confusion around this steel callout.  Actually you won't find a Mil-Spec that states 41V45 (or at least I have not been able to locate it).  I believe the actual Mil-Spec reference is to MIL-E-11595E and the steel identified in the Mil-Spec is Chrome-Molly-Vanadium (CMV) and 41V45 is another informal term that seems to be adopted by many manufacturers.

The top of the barrel is marked with "5.56 NATO 1-9" which is the caliber (5.56 NATO) and barrel rifling twist rate (1 full twist every 9").  The rifling is also a 6 groove right hand twist.

Figure 20
Ruger SR-556C Review

The bottom of the barrel is marked with "BEFORE USING FIREARM READ INSTRUCTION MANUAL" which is always a good idea.

Figure 21
Ruger SR-556C Review

The other significant feature of the Ruger SR-556C that is different from the other SR-556 models is that they fluted the barrel in the area under the handguard as shown below. There appears to be 6 flutes measuring about 5.75" in length.  This fluting accounts for the other half of the weight savings for this rifle and it also comes from the front which helps make the rifle more point-able (less inertia in the front of the rifle).

Figure 22
Ruger SR-556C Review

 

Pistol Grip

The pistol grip on the SR-556 is a Hogue® Monogrip® Pistol Grip and has the Ruger symbol included on both sides.  This grip is comparable to the Hogue Model 15000.

Figure 23                                                            Figure 24
Ruger SR-556C Review   Ruger SR-556C Review

The bottom of this grip is open and will allow use of other accessories such as the Samson Field Survival Kit.

Figure 25
Ruger SR-556C Review

Buffer Tube and Buttstock

The rifle comes with a six position Mil-Spec diameter buffer tube.  This tube can accept a wide range of aftermarket buttstocks.

Figure 26
Ruger SR-556C Review

Figure 27
Ruger SR-556C Review

The buttstock is a very simple collapsible M-4 style buttstock that includes a toe-mounted sling swivel and integral slot to allow attachment of a variety of sling types.  As with nearly all buttstocks of this simple type, there is rattle of the buttstock on the buffer tube.  Considering the wealth of buttstocks on the market and that Ruger is already supplying Magpul components, this is the one area that I think could be improved with a Magpul buttstock.

Figure 28
Ruger SR-556C Review 

Figure 29
Ruger SR-556C Review

Figure 30
Ruger SR-556C Review

Figure 31
Ruger SR-556C Review

Figure 32
Ruger SR-556C Review

Sights

The Back Up Iron Sights (BUIS) on the Ruger SR-556 rifles are manufactured by Troy Industries.  I was not able to find an exact match of these sights at at the Troy Industries (TI) website so I believe that either these sights will be new models for TI or they are being made custom for Ruger with the Ruger logo applied.  If you look in the Instruction Manual (page 31 & 32) you will see that the sights on the rifle do not match that shown in the manual.

Figure 33
Ruger SR-556C Review

The key difference with the sights on the Ruger SR-556 and the ones in the Instruction Manual are how they are clamped to the rail.  You can see below that there are two splits in the sight base.  When you tighten the screw, it actually bends the two sides together to clamp on the rail.  The models in the Instruction Manual have a separate piece on one side that is used to clamp the rail (more traditional style of clamping method).  The advantage to the new style is you have one less piece of hardware and this is a more sleek design.  The disadvantage is that if you want to remove the sight, you must slide it down the rail and remove it from the end of the rail.  You can not pull it out or drop it in place on one of the rail slots. 

Figure 34                                                                    Figure 35
Ruger SR-556C Review   Ruger SR-556C Review

Both sights will flip up and lock in place without having to push any button.  Pushing the button on the left side of the sight is required to unlock the sight and flip them back down.

The next series of photos gives you a good idea of the configuration of the rear sights. The comparable sight at the Troy Industries website can be found at this link.  The Ruger sight includes two peep hole sizes.  It looks like the Instruction Manual cut off the information related to the windage adjustment per click, but the Troy Industries site states  0.5 MOA per click adjustment on windage.  This is close enough and keep in mind that with both windage and elevation adjustments, the actual values are based on the distance between the front and rear sight.

         Figure 36                            Figure 37                           Figure38                            Figure 39
Ruger SR-556C Review   Ruger SR-556C Review   Ruger SR-556C Review   Ruger SR-556C Review

Figure 40
Ruger SR-556C Review

The next series of photos gives you a good idea of the configuration of the front sight. Overall, I'm a fan of the HK style front sight and I'm glad to see Ruger put a quality sight on this rifle platform.  The comparable sight at the Troy Industries website can be found at this link.  Based on the Instruction Manual (page 31) 1/4 turn of the post will give a 2" shift in elevation at 100 meters.

            Figure 41                        Figure 42                           Figure 43                           Figure 44
Ruger SR-556C Review   Ruger SR-556C Review   Ruger SR-556C Review   Ruger SR-556C Review

Figure 45
Ruger SR-556C Review

These sights together weighed in at 0.200 pounds (3.2 ounces).  If your planning to put a fixed mounted optic sight on this rifle that does not allow co-witnessing, I suggest you take these off to save weight.

Figure 46
Ruger SR-556C Review

Rail Covers

The rail covers are also manufactured by Troy Industries and have  the Ruger logo and name printed on one of the three provided.  You can see the details for the rail covers at the Troy Industries website by looking at this link.  The rail covers weighed in at 0.222 pounds (3.55 ounces).

Figure 47
Ruger SR-556C Review

Figure 48
Ruger SR-556C Review

Magazines

The rifle comes with 3 Magpul PMAG 30 Standard magazines.  A single PMAG weighed in at 0.304 pounds (4.86 ounces) without the impact/dust cover.

Figure 49
Ruger SR-556C Review

Figure 50
Ruger SR-556C Review

Total Weight

The rifle weighed in at 7.214 pounds without the sights, rail covers and magazine.  With these accessories, it weighed in at 7.940 pounds.  Depending on how you want look at it, the 7.40 pounds advertised seem like a legitimate weight for the rifle, but with everything installed and no bullets, it is nearly an 8 pound rifle.

Figure 51
Ruger SR-556C Review 

Figure 52
Ruger SR-556C Review

More Overall Photos

The next series of photos is to give you some more overall perspectives (views) of the Ruger SR-556C rifle.  These photos are at an even higher resolution than the normal photos so you can see even more detail.  The UTG OP-1 Bipod does not come with the rifle.

Figure 53
Ruger SR-556C Review 

Figure 54
Ruger SR-556C Review

Figure 55
Ruger SR-556C Review

Figure 56
Ruger SR-556C Review

 

In the next section, Part 4 of this review, I cover the disassembly and the internal features of the rifle in great detail.  You can go back to Part 1 of this review for links to all the other parts of the review.


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