January 2010

DIG v. GPS: Are Gas-Piston ARs Worth Their Premium Prices?

We’d buy the impingement Stag 2T ahead of Ruger’s gas-piston SR-556, mainly on cost. The High Standard HSA-15 isn’t bad either, but it lacks some niceties we’ve come to expect.

New AR-15 shooters—and there are hundreds of thousands of them in the last five years—face a bewildering set of choices when they consider buying a new rifle. Chambering (what’s the difference between 223 Rem. and 5.56 NATO, and can the rounds be shot interchangeably?), features (rails, grips, handles, sights), and even color (basic black, sand, olive drab, or multiple color tones) are among the decisions the new buyer must ponder. And, of course, there’s price, and now, gas mechanisms. The appearance of gas-piston systems in ARs has been variously hailed as a game-changer and as nothing special. Gun Tests readers have been asking for tests of gas-piston system (GPS) guns, and we are nearing the completion of head-to-head tests of several of those guns. But is standard AR direct-impingement-gas (DIG) operation going by the wayside?

Perhaps, but we don’t think so. There are many very good guns that work with the proven DIG system, and if GPS does supplant DIG, that sea change will be many years coming. But as for today, we wanted to find out if a GPS gun was worth hundreds of dollars more than two cheaper DIG guns at various price points. Our contestants were the High Standard HSA-15 Flat-Top Carbine No. HSTX6551, which lists for $920 and carries the dual-caliber designation of 5.56 NATO / 223 Rem. It is a direct-impingement unit like the Stag Arms Model 2T 5.56x45mm NATO, $1125. Pitted against these two traditional mechanisms is Ruger’s new SR-556FB 5.56x45mm NATO-223 Rem., a gas-piston gun that has an MSRP of $1995, but which commonly sells for around $1700. That’s a $575 premium above the Stag and a whopping $780 jump above the High Standard. But to see if those numbers reflect true value or simply fewer useful features, we had to get down in the weeds and shoot the guns side by side and see what we liked and what we didn’t. But first, let’s look at how the guns differ internally.

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