Best piston AR-15

IMHO the best one is the one you don't buy ! Seriously the DI guns if built correctly have proven superior and certainly will be easier to keep running in the hard times ahead. IF you have to have one then an FN SCAR or HK 416 is probably best.

Deserthunter: I've also read excellent reports on the XCR rifles by Robinson Arms: .223, .308 etc.
Youtube "Falia XCR" for a nice field strip of the .308, and methodical re-assembly. Pleasant female voice for the narration.

* Piston-driven, very interesting guns which missed the SCAR competition when they reportedly didn't send in the BUIS data on time.

I have to agree with Gordon (except that an AR isn't direct impingement. Nothing personal, Gordon.)

Make your life easy and follow Gordon's advice.

Pistons are fun.
It’s just another way to move the bolt.

Adams Arms is a good rifle with a pistons setup. I like mine, as it was a little more affordable than a LWRC or FN.

I have built a Superlative Arms piston into a rifle before as well. I really like it. Much more adjustable than the two setting Adams.

Pistons are great.

However, the gas tube on an AR is not a detriment.
The less moving parts the better, and a piston incorporates more moving parts, needing lubricant and maintenance.

I have both, because, why not?

But if one found a good deal on a rifle in either format, don’t pass it by. There really is not a huge difference to civilian use.

There is a reason the military uses a gas tube.
(Humans are forgetful, and hard on things. A bent gas tube will work, a bent op-rod might not...)

I have 1 piston AR, it is an Adams Arms AR10.

The rifle shoots great, I have several DI Ar's too and they are good shooters too.
I have no preference for one over the other, but, piston systems can have proprietary parts not available at you LGS.

LWRC manufactures very nice ones.

LWRC, H&K, Sig MCX and FN SCAR would be my top choices. I have owned LWRC and SCARs. I currently own an MCX and I like it a lot. My personal preference of the rifles I have owned would be the LWRC. I really like everything about the MCX other than the over-sized hand guard. May look into trading it in on an LWRC piston-driven rifle.

I also owned an Adams Arms piston driven 308 and though it was accurate, reliability was sub-par. Every DI rifle I’ve ever owned was more reliable than the AA rifle I had.

I have a piston drive Ruger SR556. Excellent gun. The system has an adjustment knob that i have never turned.

I think @Gordon is right. Keep it simple

I have used the HK 416 and the LWRC M6, considered to be the "top tier". Not impressed- still sticking with my DI guns.

Just through dumb luck, I actually have more piston guns than DI- CMMG and POF. My experience has been that there is no apprecciable difference in accuracy, reliability, cleanliness, heat distribution, or perceived recoil. They are all very good rifles.

However, the bulk of the piston is always going to limit your handguard options, and proprietary parts will be impossible to source after a "destabilizing situation," so for serious duties I prefer the GI standard.

The only external piston driven AR I have is the Taiwanese one from Wolf based on the T91. I wanted a rifle that was actually designed by engineers and the T91 is Taiwan’s 2nd generation.

Things I appreciate about the T91 are:
The gas system is protected by a stainless steel sleeve that also contains all the parts and allows for easy disassembly out the front 9f the rifle w/o needed to remove the hand guards.
The op rod has different diameters on it so you literally can’t assemble the darn thing wrong.
The op rod bearing surfaces are steel, so you have steel on steel contact instead of steel on aluminum.

BSW

Probably the best reason for a piston AR-type rifle is that you can put a folding stock on it. Examples are the Armalite AR-180 and the Daewoo K2.

I would definitely go with a T91 or BRN180. With either one you get a great piston AR style gun plus a great story.

AlexanderA said:

Probably the best reason for a piston AR-type rifle is that you can put a folding stock on it. Examples are the Armalite AR-180 and the Daewoo K2.

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Can’t agree with that one. Piston up front or in the bolt and bolt carrier doesn’t make any difference as to the location of the recoil spring. Without a major redesign of the AR lower receiver you’re stuck with the original straight line recoil path that precludes folding the stock. The AR180 and K2 (or K1 for that matter) aren't ARs and don't use AR receivers.

BSW

The BRN180 is the exception to this rule as it has dual recoil springs on guide rods (AR180 design, hence the name) , so folding stock is totally viable. Brownells even sells a 180 lower with pic rail instead of threaded tube style lower to accommodate a folder.

https://www.brownells.com/rifle-par...tripped-lower-receiver-forged-prod130438.aspx

I've been very happy with my Primary Weapons System Mk114 Mod 1. Yeah, it's proprietary but made across the border in Idaho. They've been around for awhile so while it maybe isn't your gun for TEOTWAWKI there should be no problem keeping it running for the foreseeable future. It's true that a piston gun like this won't have so many handguard options but the one supplied is very nice. Guess I'm not as much into Barbie dressup or LEGO as some. I like to set up all my long guns pretty much the same way- light, RDS & sling and not much else (save a stubby VFG).

It's not an AR but I'm even more pleased with my CZ Bren 805. And yeah, it's kind of a white elephant in the sense that parts will be impossible to source if things go pear shaped (and probably even before that). I've contemplated selling the thing and getting something mainstream and off-the-shelf but man, it's such a sweet shooting gun!

Notice the best piston ARs are guns built from the ground up to be piston guns. Many really aren't even ARs anymore.

When you shoehorn a piston into a standard AR you have compromises.

Kalashnikov.

C-grunt said:

When you shoehorn a piston into a standard AR you have compromises.

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While I agree that everything is a compromise, the short stroking Adams Arms, Superlative, and POF all replace only the gas block, key, and tube.
These can be made with proprietary bolt carrier, or just a gas key replacement with a flat strike face. All mine fit under common hand guards, although the Superlative by just barely.

None. It's like adding tassels to your Harley.

d2wing said:

None. It's like adding tassels to your Harley.

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Tassels on the Harley will at least help the tow truck find it. Although I guess he could just follow the trail of oil, too.

The biggest problems I see with a piston AR are the proprietary nature of the action parts, the fact that many (most) piston guns seem to add a pound to the weight, and $1k to the cost. There are several piston guns which mitigate these problems, but I think I would tend to the BRN-180 for myself if I ever acquire a piston gun.

i like the piston systems because they run a lot cleaner. most rifles in the future will have piston systems, i think what i'm going to do is wait and see what the military adopts and run an ar15 with that system, but i do like the pof piston ar's and i've been looking hard at that stag arms 8L (i'm a lefty)

Broccolis said:

i think what i'm going to do is wait and see what the military adopts and run an ar15 with that system,

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I think it’s been called...
The piston isn’t new, and .mil has been running DI rifle for infantry for the last fifty-sixty-ish years.

But, they have also been running piston machine guns for as long too.

You may just have to decide.

Or do what I do. Flip an Oreo.
Grab Oreo the DitchTiger, flip him once, gently, on the couch.
If he then tears your arm off, get a piston gun.
If he tears most of a thigh off, then it’s the DI rifle.
If he just rolls over to pet his tummy, it’s delayed blowback time!
(Don’t pet his tummy. It’s a ruse. He just wants to shred the hand that dares touch the white belly. Don’t fall for it.)

He’s my best decision maker.