Piston-driven AR-15s saw a steep rise in popularity around 2010, but over the last few years, many users have shifted back toward the standard direct impingement system of the AR-15.
However, piston-driven guns still remain attractive for some shooters.
They run cleaner and cooler than a standard direct impingement (DI) system, making them a big draw for high-volume shooters and those who run suppressors.
They also just make all-around great guns, especially if you want to try something a little different. Who knows? You might just fall in love.
Unfortunately, not everyone has the kind of cash required to pick up a whole new gun just to give this fancy piston thing a try…which is totally understandable.
So what is the solution? Let’s take a look.
Summary of Our Top Picks
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Best Budget Piston UpperWith various models and starting as low as around $600, these are the most affordable way to get into a complete piston upper.
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Editor's PickPrimary Weapons Systems MK116 MOD 2-M Upper
The MK116 is true top-tier piston upper that comes in at a lower price point than many of its competitors with comparable specs.
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Best Top-of-the-Line Piston UpperThe LWRC IC-SPR is bona fide premium duty-ready weapon. Although it is expensive, this upper has it all.
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Best Piston Conversion KitAdams Arms P Series Micro Block Mid Length Piston Kit
As far as direct impingement to piston conversion kits go, Adams Arms is arguably the most accessible and most affordable.
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Getting a Piston AR-15 Without Breaking the Bank
Well, if you’re anything like me when I started out, you probably already have a cheaper DI AR-15 lying around.
If that’s the case, you can simply switch out the upper receiver with a piston-driven upper receiver and be on your merry way, or you can use a kit to convert your DI system into a piston one.
If you don’t already have an AR-15, I highly recommend picking up a DI gun first before springing for a much more expensive piston-driven one. If you need help choosing your first AR, I recommend giving our AR-15 Buyer’s Guide a look.
Why Choose a Piston AR-15?
This is going to be a bit of a Coke vs. Pepsi, Ford vs. Chevy, Superman vs. Goku type of deal, so it’s important to understand right away that a lot of this is going to come down to personal preference.
However, there are some tangible benefits to choosing a piston AR, but you’ll have to decide if they’re worth it to you
Also, the correct choices are Coke, Ford, and Goku — you can tell me why I’m wrong in the comments.
Benefit #1: No Gas Blowback into the Breech
With a piston AR, you get just a small amount of powder fouling in a small, contained area around the piston itself. Why does that matter?
Well, with a standard DI AR-15, you get exhaust gases and powder coming back into the breech.
This means all that crud and junk from firing winds up in your lower, chamber, and other critical areas, making for a much dirtier firearm. This means more frequent cleaning is required if you want to avoid any fouling-related issues.
Meanwhile, a piston AR funnels all that gas and powder fouling into a contained area (face of the piston), which makes a piston AR a much easier beast to clean and maintain.
Benefit #2: Heat Displacement
You know how other guns get hot when you shoot them? Yeah, the same thing happens with AR-15s.
However, for really high volume shooters, like if you have a legal fully automatic lower or you shoot competitively, you can keep your gun a little bit cooler by swapping to a piston system.
This is because, again, you’re not dumping hot, nasty gases into the main body of your firearm anymore. Instead, the gasses are primarily contained forward of the bolt.
Downsides to Piston AR-15s
Now, it wouldn’t be much of a choice if that was the whole story. There are some downsides to the piston lifestyle that I want to go over as well.
First, they’re pricey.
Some of these upper receivers alone cost as much as a fully-kitted direct impingement gun. But, for some people, that’s okay.
Second…parts can be a bear to find and match up properly. Piston systems aren’t necessarily standardized like direct impingement systems.
If you go with one manufacturer, you’re stuck with them, so make sure you choose one that has a good track record and will be around in the future.
Lastly, since there’s more metal stuff above the barrel, the gun can become front-heavy. I haven’t found this to be a serious hindrance, but it’s a little different from your normal DI gun.
So, with all that being said, let’s get into some of the best piston uppers and upper conversion kits on the market.
Best AR-15 Piston Uppers
1. POF P-415 Edge
The POF P-415 Edge packs a ton of features at its price point.
Prices accurate at time of writing
Prices accurate at time of writing
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This short-stroke piston upper sports a nitride heat-treated barrel, heat sink barrel nut, roller-cam pin bolt-carrier group, user-adjustable gas system, muzzle brake, a full-length M-LOK rail with QD sling points, and POF’s patented E2 extraction technology.
Patriot Ordnance Factory has been making the Edge and improving it since 2002. This upper is a proven design that gets you all the premium features out of the box without needing to spend extra money on upgrades.
2. Adams Arms P1/P2 AARS/P3 AARS Uppers
The P1/P2/P3 series from Adams Arms is a great choice for a solid, reliable, piston upper.
Prices accurate at time of writing
Prices accurate at time of writing
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Basically, the P1 is their basic entry tier upper that comes in around the $600 range. The P2 is their standard model at around $850. Lastly, the P3 is their higher tier upper designed for competition or duty use and is reflected in the near $1,700 price.
If you step up to the P2 and P3 series, you are treated with a high-quality free-floated M-LOK handguard. The P3 model even comes equipped with a carbon-fiber barrel and muzzle brake installed for those who are lightweight and speed-oriented.
These short-stroke piston uppers function flawlessly with proper maintenance when used in conjunction with a quality mil-spec lower.
Another great thing is the mid-length gas system. I think it is the best of both worlds and splits the difference between the shorter carbine and longer rifle uppers, which makes this a bit of a Goldilocks upper.
3. PWS MK116 MOD 2-M
When the apocalypse has come, and you’re digging through the local gun store to try and build something that will help you survive the wasteland that our world has become, the PWS MK116 MOD 2-M is the one.
All kidding aside, Primary Weapon Systems has made what is, in my mind, one of the very best drop-in, no-fuss, shoot-all-day, piston-driven upper on the market today — they are an industry standard and a common recommendation for all the right reasons.
This upper has all the features you could possibly want, including the unabashedly cool PicLok System that allows you to use M-LOK and Picatinny attachments. It also features a 1:8 twist barrel, long-stroke piston, Radian Raptor ambidextrous charging handle, a 3-position adjustable gas system, and a muzzle brake.
Prices accurate at time of writing
Prices accurate at time of writing
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It also has a forged 7075 aluminum upper receiver, making it stronger and yet lighter than some competing billet receivers.
PWS rifles are known for their accuracy, quality, and reliability in the world of piston guns. If you are looking for a universal recommendation, this is about as close as you are gonna get.
What do you think of PWS? Rate them below!
4. LWRC IC-SPR Upper Receiver
Without a doubt, LWRC makes some of the best piston uppers in the business, and the IC-SPR upper is a prime example of top-tier manufacturing
The IC-SPR upper uses LWRC’s patented short-stroke piston for ultimate reliability. You also get a NiCorr treated cold hammer forged, fluted heavy barrel, a nickel-boron bolt carrier group, a modular rail system, ambi QD sling mounts, ambi charging handle, and iron sights.
All of the materials used by LWRC are meant to survive the harshest conditions while reducing wear and tear.
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If you want an absolute top-of-the-line piston-upper, LWRC is hard to beat.
AR-15 Piston Conversion Kits
1. Adams Arms P-Series Micro Block Piston Kit
Now, if you don’t want to buy a whole new upper, there are also a number of gas conversion kits out there that will take your DI gun and convert it to a piston system.
I’ve tried several, and I hated all of them except Adams Arms.
Prices accurate at time of writing
Prices accurate at time of writing
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The Adams Arms Piston Conversion Kit will let you convert your DI upper into a piston upper with a minimum amount of fuss. Kits are available for carbine, mid, and rifle-length uppers.
I love their piston system; I’ve used two of their older ones, and I couldn’t be happier. The newer P-Series kits cut down drastically on the weight and front-heaviness, almost to the point where you can’t even tell it’s a piston gun.
Coming in at around $270 to $300, this is one of the most affordable ways to dip your toes into the world of piston-driven AR-15s.
2. Superlative Arms Adjustable Piston Kit
I love Superlative Arm’s adjustable gas block. In fact…it’s the only one that I use now. See our full review.
While I haven’t tried out their piston system yet, I am eager to give it a shot due to it having the same rave reviews as their renowned DI gas blocks.
Prices accurate at time of writing
Prices accurate at time of writing
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I also appreciate how you can easily find the different gas lengths for the Superlative, as well as pencil barrel sizes in stock.
Final Thoughts
That about does it for this one, guys and gals. I hope these recommendations help those looking for a piston-based AR-15 upper.
Do you use a piston upper? Did you switch back to DI? Let us know in the comments!
Want a normal DI upper? We’ve got our favorites in our Best AR-15 Upper Assemblies for the Money guide!
89 Leave a Reply
Are there any piston kits for side charging AR uppers?
Can you comment on the ADCOR Bear elite piston AR15?
Forgot to mention the t91 wolf upper unless it wasn't out at the time of this article
Probably worthy to at least mention that none of the POF offerings have a full-auto capable BCG, so not worth investing in a binary trigger solution. With that said, I own a POF Revolution 18" Gen 4 (.308) and it is by far the best AR I currently own and will likely take it with me to my grave!
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Do these piston conversion kits work with other calibers, such as 7.62x39? What about using one with a Gibbz side charging upper receiver?
I like this list, but I would say POF-USA P415 EDGE, and the LWRC IC-A5 are a toss up, as far as quality, and which one is best!
I was really surprised the Superlative Arms (SA) piston conversion kit was mentioned so late in the article. After much research, I chose the SA kit for the removal plug that allows for quick removal of the piston/rod assembly for cleaning without any further disassembly. I bought one SA kit, then two more, as I found the kit to be EXCELLENT, and more than met my needs! The BCG was cool to the touch after 50 rounds of .223 and the barrel & chamber were the only items that needed cleaning. I have several DI ARs, but when SHTF time comes, my piston kit ARs will be on duty! The provided carrier is also well made, and I whole heartedly recommend the SA piston conversion kit without hesitation!
Outstanding summary for a guy who has not handled a AR 16 platform since the 1980s. Trying to catch up.
I appreciate all of your comparison and review articles. It's worth noting that Superlative's piston kits are NOT rated for 300 BLK, however, Adams Arms does have one specifically for 300BLK. An SBR in 300BLK would benefit from being piston operated, if for no other reason than reducing internal fouling.
can i convert a ar 45 gas blowback system with no gas port in the barrel to a piston system
Looking to make a build with PWS reciver extension and either SA or AA piston conversion kit. Will this build function like the HK 416 during HK's SOCOM water test?
The water test is more than the piston kit. Their lower is where they shine. Only an HK will function like an HK. If you need an AR that will see service where immersing in water will be common , buy the HK. They are made for severe service. Every part is designed for hard service.
The PWS in the pic is MOD 1. The MOD 2 has no forward assist. Otherwise a fantastic article. I personally love piston guns. My 1st AR was an Adam's Arms 16 inch. Great gun insanely reliable. Now I have numerous AR's. My favorite is my PWS MK111 MOD 2. It is an absolute tac driver! I shot both of the Barret options and wasn't overly impressed to be honest. Plus the Barrets are noticeable heavier then the PWS. I run all my ARs suppressed so piston systems are the way to go. Please keep up the great work, I appreciate you articles. Thank you!
We're in the process of updating some of these older articles so they're more current and correct. So, thanks for pointing that out and for reading!
I have the mossberg mmr.
Could anyone tell me if, and what poston System will fit the 16 inch barrel model
Hi
Will the Adams Arms Piston Kit (P-Series) work with this
PSA 11.5" 5.56 1/7 PHOSPHATE 10.5" M-LOK UPPER - WITH BCG, CH, & MBUS SIGHT SET AND BUSHNELL TRS-26 RED DOT
Regards
Will this work in a left handed upper or do they make one for right handed
Any piston kit that comes with a bolt carrier assembly included in the price will be right-handed only. You can take that bad news to the bank. The ONLY after-market piston kit (that I’ve ever found) that can be fiddled with to work with a left-hand upper receiver is Adams Arms. And that’s been a while back; Adams Arms went “tits up” (bankrupt) a while back but someone bought them and trimmed the product line … and may have (permanently?) dropped a key component that makes the L.H. conversion possible, circa 10/2021: The FGAA-10053. This little item replaces the standard Gas Key on any AR-15 bolt carrier to give the piston op rod something to push against - and unlock the bolt. I bought two years ago, used one and have misplaced the other. But before that happened, I created my dream upper half from a Stag Arms L.H. stripped upper, Stag Arms L.H. Bolt Carrier Group - removing the standard gas key and replacing it with this FGAA-10053 - new mounting screws re-staked + Loc-Tite - and adapted the bolt per Adams Arms instructions. Went with the mid-length gas system and a super-duper 16” mid-length 416 st. stl. barrel from Black Hole Weaponry. It’s my dream-come-true rifle.
Could you use the superlative kit to convert an upper chambered in 7.62x39? Ammo prices are ridiculous but steel case Russian ammo is still dirt cheap. I hate running steel in my DI rifles.
Good luck finding a Superlative Arms Piston kit. Very back ordered from the vendors I’ve emailed. I own three .750 set screw 16” Mid-length precision PROOF .223 wylde, .625 set screw 11.5” Carbine 5.56 and 0.750 clamp on 16” Carbine 7.62x39. The latter is what I think you are asking about and while SA doesn’t say its tested with 300blk, much less 7.62x39. 7.62x39 with the SA kit works superb. Carbine length is really needed to cycle the BCG and get lock back at fully open. I have a fourth build waiting for another batch of SA kits. I’m kicking myself for not buying it when I saw it in stock. A week later it was gone. Good luck.
Noob here. Curious what you mean by "Carbine length is really needed to cycle the BCG and get lock back at fully open"? You mean if you went with a longer length you might not be able to cycle properly? Was thinking about longer lengths as I've read a bunch of articles about softer shooting with the longer length gas systems.
Looks like a few who are interested in shooting (cheap but dirty) 7.62x39 are here. On the SA kit would you recommend clamp or set screw, or is either one fine? Sounds like one will need to take whatever they can get but I was wondering anyway. Thanks.
2020 update? Adams P-series kit from 2017 has been discontinued. Thoughts on the Superlative Arms kit?
I'm a newbie and want to build an upper with piston kit from the get-go. Consider new article?
We have this article on the list for major update soon! The Superlative Arms kit is good to go! If you're looking for a piston upper that is ready out of the box, you might want to take a look at the Brownells BRN-180.
I was also wondering about this as this article mentions the SA adjustable gas block and mentions wanting to try their piston kit so would love to know the results of that.
Many of the parts on this list are discontinued. I would love to see an updated list.
Would these work for 300 black?
Super-sonic yes but not subs. Tried a superlative arms kit on a 16” rifle. Had a pistol length gas system and a tuneable jp scs and still wouldn’t cycle subs at all unless suppressed
I think this article needs to be updated because the best budget piston upper right now is the Wolf A1, which you can get for $449. It has been very well-reviewed and is essentially an import of the T91 upper used by several militaries around the world.
I got a Wolf A1 on sale for less than $449 on sale and its great. People who pay attention are always....'....hey, what upper is THAT?'
Would recommend, would buy again.
I run a Sig 516 on an AP lower with a Geissele FastFire (lighter trigger spring) and am pleased with this one. very accurate, clean running and smooth to shoot. I would like to swap out the handguard for a lighter M Loc.
I have both the Adam's (AA) and the Superlative (SA) mid, adjustable, lo pro kits mounted. They both work well. I prefer the Superlative kits for these reasons: 1) The SA kit allows for the removal and cleaning of the op rod and spring without dismounting the gas block. With the AA kit, one must take off the gas block to remove / replace the op rod and spring. The AA gas block requires a hydraulic press to install or remove it. 2) The SA kit will allow the use of many more different free float rail systems. There is no dependence on what is a highly customized barrel nut as in the AA kit. 3) The AA kit's dependence on the use of the milspec barrel nut, or their proprietary barrel nut, forces the selection of the AA free float rail system as the only "affordable" option. AA lists others on their website, but most us a GI barrel nut, or cost a bunch of money. My AA rail had alignment issues, I sent it back.
The AA system does have the op rod spring outside of the gas flow, and so is protected from it. The SA kit has the op rod spring in the high temp gas flow, so there's a question how many firing cycles it will withstand before needing replacement.
What? Need a hydraulic press to install/remove the AA gas block? Wouldn't that just about eliminate most people?
Your own admission: "Well, with a standard AR-15, you get exhaust gases and powder, and all that crud and gunk that comes from firing a gun dumped right back into the breech."
That Sir, was reason enough for my first three AR's to be piston-operated.
Don't drink soda, Ford sucks and wtf is a Goku?
The Adams Arms conversion works real good and I bought it from Midway before I read your review. Thank you
should i just get the LWRC piston gun and be done with it??
Lwrc or POF either one you will be very happy with, POF has some of the best customer service in the bussiness right now, and a really good lifetime of the GUN warranty, that follows the gun not the owner. LWRC Makes some really beautiful gun well made guns as well I personally own 3 POF's and one LWRC six8. I do t think you can go wrong either way, if your looking at piston guns the main four in my opinion are POF, LWRC, PWS, AND LMT.(lmt does some really cool stuff as well, a d they do have a pretty good piston option, BUT in my opinion, it is not their specialty like the three others.) Hope that helps. P.s. this article is extremely poorly written, and inaccurate so take what you learn from it with a grain of salt.
I also agree with Eric, I own a few POF’s and very happy with them (you get what you pay for).
I think they have to give a DGI operated rifles credit for something so, they selected accuracy. I say maybe - if it's tuned like a concert piano. Like you, I'm a piston guy owning 3 PWS and 1 Adams Arms.
They're outfitted with combat sights, i.e., Trijicon ACOGS with RMR's perched on top of 'em. They're nothing shy of combat accurate. Even the 7.62 x 39 PWS shoots phenomenally.
My advice, especially if you're new to this game, save up and purchase a piston-operated AR.
Rationale: The guys that purchase a DGI end-up dumping money into adjustable gas blocks, BCG's, ambi charging handles, and buffer springs and/or buffer weights. Now, you're at or very close in price to an entry level piston-operated rifle.
Neither piston-operated nor DGI-operated Mil-Spec rifles come with sub Mil-Spec trigger pull. So, IF accuracy is paramount, plan on adding an aftermarket trigger and trigger pin anti-walk kit. For the record, MIL-C-71186 states 5.5-8.5 pounds trigger pull. I'm not certain but for liability, I reckon manufacturers are reluctant to install a lower trigger pull on a semi-auto rifle?
I prefer shooting and cleaning the gas piston over the direct impingement. The gas piston has a little less recoil too.
I gotta say this article sucks! Its full of errors, one big one is that the PWS FULL RIFLE SHOWING IS THE MK1 MOD1, NOT MK1 MOD2. The MOD1, has a forward asisst the MOD2 does NOT. ALSO almost every RIFLE maker that makes a piston rifle WILL SELL THIER UPPERS SEPARATELY, So not sure where that came from. Also Barrets upper is not one of the most expensive out there, its on PAR with all the other HIGHEND piston systems, you have just picked it to compare to all the bottom end ones. PWS IS MIDDLE GROUND, BUT the rest are low entry level systems, the PRICE POINT for the Barret is similar to LWRC, LMT, And alittle higher then Sig, and POF, (which for me is probably the best bang for your buck piston rifle), but if you put the Barret next to lets say a H&K 416 upper, or even an MR5.56 the BARRET look positively cheap in comparison. So idk just my two cents. There was other errors as well but those are the most glaring. Idk you guys gotta know this stuff I am not some expert, so what up with that? Did those brands not send the monthly check or something???
Can anyone tell me if these conversion kits will work with my current free float rail system? Its a Leapers UTG super slim 13 inch