Finally, we have a new piston-operated AR-15! I can’t believe we got along with only being able to choose from the H&K 416, Barrett 468 … errr, REC7, POF / Bushmaster, Ruger SR-556, Colt 1020 … whoops, you can’t have one, the Titan Defense 416 clone, SIG’s 516, the design I shot last year at carbine class that I can’t find any info on now, the CMMG design, the Adams Arms drop-in unit and probably a handful of others I’ve forgotten.
And if you decide to stray off the Stoner reservation, you may also select from the SIG 556, the various AUG clones, the FN 2000, the FN SCAR-L and the Robinson XCR.
That said, I am enthused about the S&W version, not because I’m more confident in their particular design, but because the marketing power and weight of the S&W rollmark makes this rifle the front runner to achieve market dominance and force some level of standardization to a confused marketplace.
On the third hand, I am yet to be convinced that the usual AR shooter requires a piston gun. The only reason I would choose one is if I regularly ran the gun with a suppressor. Otherwise, and this is some gen-u-ine gun-guru wisdom I’m about to drop on y’all, but if you want a truly reliable AR, get a 20″! A 20″ rifle with a rifle length gas tube, a chrome lined chamber and bore, a correctly dimensioned 5.56 NATO chamber, a correctly aligned gas tube with staked carrier key screws, using Magpul PMAGs, and a fresh extractor spring with black insert will be as reliable a rifle as you could ask for. The gas piston assembly offers additional parts and points of failure, extra weight and bulk, but somewhat cleaner running. Contrary to hopes, heavy use seems to disprove the idea that piston operation extends bolt life in short barreled guns that see a lot of full-auto fire.
Direct impingement gas system rifles are successfully used by every military unit and police department that actually matters on Earth. If you think you know rifles better than all of those guys put together, knock yourself out!