If you want a piston AR go with Ruger. I think it’s the best value for such a gun on the market and they are pretty close to 100% trouble free.
However I would point out a fact to you and the readership.
In semi-auto guns the piston is a perfect answer to a non-existent problem.
The thing that has caused failures in the M-16 family of rifles and carbine in the US Military’s action is heat. The idea is not valid that the “cleaner piston guns” make them work in sand better. They don’t
The heat from the Stoner system dumps on top of the bolt from the gas key in the carrier. The bolt heats up in full auto fire and in some actions, the amount of FA fire is enough to get the bolt over 900 degrees. I have heard from some folk in Va that it can go even hotter in some cases.
If you take steel and heat it quickly and cool it slowly, and if you do it enough times, you can soften the steel. It’s called annealing.
So, the bolt body gets hot. It cools slowly. It’s hot right where it’s the thinnest, at the cam pin hole. If that gets a bit soft it can elongate in use. Only a few thousandths is enough to make the pin “slap” back and forth as it locks and unlocks. As that continues you see cracks develop at the pin hole. After time the crack can turn into a break, and then you have a weapon failure.
So the piston guns dump the heat outside the action not in the action and the bolt never gets very hot.
For FULL AUTO!
Note; such a system does NOTHING to keep sand from getting between the bolt and the receiver, so the idea that it’s “better” in the sand is not really true.
You still need to lube them. And lube does attract sand. And the lube will burn off on full auto guns a LOT faster than it does in Semi-auto fire.
So again, the piston gun is a great answer to the problem……IN FULL AUTO!
In Semi autos you CANNOT get the bolt hot enough to soften it without having a LOT of loaded mags, a lot of ammo and a very small brain.
According to the tests we did in Nevada in 2004, firing 10 mags as fast as you could load and shoot an AR-15 (semi-auto of course) in the heat of the day, (in june) and then taking an infrared heat reading on the bolt carrier we found we could not get the bolt and carrier any hotter than 465 degrees. But 4 mags fired full auto in an M-16 got the heat up to 925.
925 will anneal most alloys of steel. 465 will not.
So I make my statement again, that for semi-auto guns the piston is not bad, but it is not doing anything of real value for you that the DI doesn’t do as well.
Also the DI system can be made into a more accurate gun than the piston system just because you can’t totally free-float a piston gun.