I will never forget how sad I was to surrender the heavy—but accurate and hard-hitting—M14 in favor of a strange-looking toy rifle we called an M16 (technically an M16A1 in my day). We Marines griped about it for decades later as, I’m sure, our predecessors griped about yielding the ’03 Springfield for the newfangled Garand, and then the Garand for the M14.

Eventually, few of us who had actually used the M14 remained. By then we had the M16A2, a very good battle rifle with very good ammunition. But looking back to when I made that painful transition more than 35 years ago, it would never have occurred to me that what we now loosely call the “AR frame” would become one of the most popular military and civilian rifle actions.

Nor, to be perfectly honest, would it ever have occurred to me that a traditional rifle manufacturer like Ruger would introduce a sporting rifle on the “AR frame.” But as Jim Bequette and I drove across Kansas toward Major Bob Stutler’s “Gun Room” in Medicine Lodge that is exactly what I expected to see. Recently retired from Ruger, Stutler and his wife, Dorothy, have been busy remodeling the old Grand Hotel, where we would join some of the Ruger folks for a first viewing of the SR-556, a brand-new Ruger rifle that looks suspiciously like, well, like an AR.

Looks Are Deceiving
Yes, the SR-556 looks, feels, and operates like the old friend the “AR frame” has become. Except it isn’t, not exactly. Custom conversions have been out there for some time, but the SR-556 is the first production “AR-type” rifle designed from the ground up with a piston action, not the familiar gas operation. The big difference is the “Two Stage Piston Drive,” wherein the gas energy drives a piston, which in turn cycles the bolt.

Is this significant? Well, according to Ruger engineers, the piston “reduces initial energy transfer, providing a smoother power delivery stroke.” Since that’s engineer-speak, I can neither confirm nor deny. I can say that I have never fired an AR that was so smooth, or so consistent. Believe it or not, felt recoil is also reduced. With a 5.56 (.223 Remington)? Does that matter? Perhaps not, but I well recall one Qualification Day when I was a captain commanding a rifle company. It was very windy and difficult, and I was snuggling tight and close to my M16 in the standing position. A bit too close: The charging handle smashed my upper lip and chipped a front tooth. I had the high score that day, but also a dentist to visit.

The difference is slight, but if you’re used to the standard gas-operated AR, you will feel it. If you can’t feel it, you will see another difference. Per Ruger: “The Piston Drive system minimizes combustion residue in the action, proving a cooler, cleaner, and more reliably running rifle.” “Cooler” I can’t address. “Cleaner” you’ll see. We had just two SR-556 rifles to play with, and we had lots of ammo. We shot it all, several hundred rounds. I have considerable experience with ARs under lots of conditions. I have never seen such little residue and grime. After a hundred rounds or more the chrome-plated bolt and carrier could be wiped spotless with a dry handkerchief (yes, Marine officers do clean their own rifles, so I know a bit about that as well).

The gas system has variable gas port sizes, the regulator offering four settings (three gas ports, plus “off”). This allows you to tune the gas system to the load. The first two gas settings are generally for “normal operation.” The “off” setting is primarily for manual operation. The highest gas setting, giving the most velocity to the piston, is intended for worst-condition use, perhaps with questionable ammo, when the rifle is dirty, or when the chips are down and the rifle simply must function.

By the way, function it does. As I said, we went through several hundred rounds with nary a stoppage of any kind. We had good ammo, both Federal and Hornady which, of course, helps a lot, but there were simply no problems whatsoever. In all that shooting we never actually cleaned either rifle, although we did wipe down the bolts a couple of times. It would perhaps be inappropriate to describe the piston action as “better”—but for darn sure it works, and I could both see and feel the difference.

Bells and Whistles
Aside from the action, the basics of the SR-556 are an extremely well-appointed “AR-type” rifle incorporating many, if not most, of the features and accessories you might see on a full-out custom AR. Moving parts are chrome-plated; the exterior is manganese phosphate “Parkerized.” The 16 1/8-inch barrel is hammer-forged, chrome-lined, of 41V45 stainless with a 1:9 twist. Slightly nontraditional, but very Ruger, is the AC556 flash hider, same as on the Mini-14.

The lower receiver is pure AR with a single-stage (and quite crisp) trigger, with six-position folding M4 stock. Buffer and spring are mil-spec, with length of pull adjustable from 10¼ to 13½ inches. Note that Ruger didn’t reinvent the wheel with the external features. The stock is a Hogue Monogrip; the handguard is from Troy Industries (its Quad Rail 1913). Those who desire can hang whatever accessories desired on the rails, up to an including a grenade launcher. Those who just want to shoot the rifle and save their tender pinkies can cover the rails with supplied Troy rail covers. And the rifle, incidentally, comes with a soft case that has three magazine pouches.

The upper receiver also has a full-length Picatinny rail. Supplied are fold-up Troy battle sights, with protected front and dual-aperture rear. One of the rifles we shot was “out of the box” with these sights; the second had the battle sights replaced with a Nikon Tactical scope. Complete with three Magpul 30-round magazines, the SR-556 is intended to come out of the box ready for…whatever.

A Joy to Shoot
That “whatever” depends entirely upon who you are, what you do, and what uses you have for a rifle of this type—but one universal truth is that all ARs are just plain fun to shoot. As I said, we ran both Rugers hard and we couldn’t make them jam. Perfect functioning aside, a couple of things struck me as we ran magazine after magazine through the rifles. First was stock fit. The fold-up Troy battle sights are fairly high, about the same height as the center of field of a normal-sized riflescope mounted as low as possible. Height of comb on the stock, at least for me, is exactly perfect for these iron sights, with the rifle coming up smoothly and perfectly on target.

Second, and please forgive me because this primarily a left-handed observation (not the same as a left-handed compliment.): Ejection is fantastic. You see, when a lefty shoots a right-handed AR there is some possibility of brass hitting one’s shoulder and bouncing down into the collar. It ain’t funny, ’cause that stuff is hot when it comes out of the action. Second-degree burns are instantaneous, and we lefties quickly learned to button the top shirt button when shooting our M16s. The SR-556 throws its brass straight out into the stratosphere, no burns and no buttoned collar.

Accuracy with the 55-grain loads on hand was pretty good. Groups with the Nikon scope averaged about 1¼  inches. And indications were that the rifle wanted to shoot better. Most groups were basically tighter, but with five-shot strings often showing an uncalled “flier,” with occasional vertical stringing. This was probably mostly our fault. Our intent was to shoot the rifles and see if they worked (they did), and we were shooting “un-broken-in” new barrels without cleaning them. Okay, I’ll admit it: We had fun running several magazines through the rifles before we got down to shooting groups. In that context, accuracy was pretty darned good. But that’s no surprise. We learned a long time ago that this type of action, mated with a good barrel, shoots very straight.

Fast or slow, bench or offhand, scope or battle sights, the SR-556 was a joy to shoot. It functioned perfectly, and did everything it was supposed to do. It’s basically an AR, and these things are true of all “AR-frame” rifles. With the gas piston, it’s an AR with a difference, and it’s also a factory rifle incorporating a wide range of popular features. Such a rifle is a huge departure for Sturm, Ruger, and Company, clearly reflecting the popularity and huge demand for this type of firearm. They’ve done such a great job with it that I hardly yearned for my old M14.


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