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Best AR-15 Piston Uppers & Conversion Kits

Everyone and their mom makes a piston AR-15 now. We go over the pros/cons of going piston, the best piston AR-15 uppers, and also the best conversion kits.

It seems like everyone and their mom makes a piston-driven AR-15 these days.  And with good reason.

Piston-driven guns run cleaner and cooler than a standard direct impingement (DI) system, making them a big draw for high volume shooters such as those who shoot competitively like in 3-Gun.

PWS Piston Cutaway
PWS Piston Cutaway

They also just make all around great guns if you want to get into AR-15’s a bit more and try something different.

Who knows?  You might just fall in love.

PWS MK1 Mod 2 Complete
PWS MK1 Mod 2 Complete

Unfortunately, not everyone has the kind of cash required to pick up a whole new gun just to give this fancy schmancy piston thing a try…which is totally understandable.

So what do we do?

Adams Arms P-Series Piston Kit
Adams Arms P-Series Piston Kit

One option is to simply switch out the upper receiver with a piston-enabled upper receiver and be on your merry way.  Or you can use a conversion kit to change your DI system into a piston one.  We’ll cover our top picks in each!

If you can’t wait…here are our picks for best AR-15 piston uppers and conversion kits:

Best Budget Piston UpperStag Arms Model 8HSC
Best Bang-For-Your-Buck UpperAdams Arms P1/P2/P3 Series
Upgrade Piston UpperPWS MK1, MOD 2
Super Upgrade OptionBarrett REC7 Gen II
(Previous) Editor's PickAdams Arms Conversion Kit (P Series)
Newer Piston KitSuperlative Arms Piston Kit

I’ve used all of them…but first let’s go over why you’d even want a piston AR in the first place.

Table of Contents


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 (but no less awesome) direct-impingement AR-15 laying around.  

Aero MC-15M
Aero MC-15M

If that’s the case, then you can just pop your current upper receiver off, and slap on a new piston-driven upper.  It’ll work just fine with your lower.

AR-15 Lower Receiver
AR-15 Lower Receiver

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 also recommend giving our updated AR-15 Buyer’s Guide a look.

So, what piston-driven upper should you get?  How do you choose?

Well, I’ve tried out way, way, waaaay too many of these things (just ask my fiancé ) so I’ve got a list of what I think are the best piston uppers currently out there.  

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.

Superman vs Goku
Superman vs Goku

However, there are some tangible benefits to choosing a piston AR.  You’ll have to decide if they’re worth it.

Also, the correct choices are Coke, Ford, and Goku, and you can tell me why I’m wrong in the comments.

Benefit #1: No gas blowback into the breech

With a piston AR, you don’t get the gas and powder fouling into the breech like you do with a standard DI firearm.  Instead, 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 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.

Direct Inpingement Gif
Direct Impingement Gif

This means all that junk winds up in your lower, which makes for a much dirtier firearm, and much more frequent cleanings if you don’t want your gun to start having some issues.

So basically, a direct impingement gun shits where it eats, which is…not ideal.

Piston AR Animation, Adams Arms
Piston AR Animation, Adams Arms

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.

PWS Piston Cutaway, Piston Highlight
PWS Piston Cutaway, Piston Highlight

Benefit #2: Heat Displacement

You know how other guns get hot when you shoot them?  Yeah, same thing happens with AR-15s.

However, for really high volume shooters, like say 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.

AR-15 Bacon Cookoff, RescueHumor1
AR-15 Bacon Cookoff, RescueHumor1

This is because, again, you’re not dumping hot, nasty gases into the main body of your firearm anymore and are instead keeping things contained.

Downsides to Piston AR-15

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.

As in, some of these upper receivers alone cost as much as fully-kitted direct impingement gun, pricey.  But, for some people that’s okay.

Khajit Has Wares If You Have Coin
Khajit Has Wares If You Have Coin

Second…parts can be a bear to find and match up properly.  Piston systems aren’t necessarily standardized like direct impingement systems.  So 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 in the front, 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. Stag Arms Model 8HSC

Best Budget Piston Upper
at Stag Arms

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons


  • Barrel Material: 16″ 4140 steel, chrome lined, government profile, manganese phosphate coating
  • 1:9 Twist
  • Muzzle Thread Pattern: 1/2″-28
  • Bolt Carrier: 1-Piece w/Integral Piston Strike Face
  • Samson Star-C free float quad rail

The Stag Arms Model 8HSC is a great budget piston upper and comes with a very usable quad rail.

Plus, you can configure your upper according to your states’ laws (hi CA, NJ, CT, MD).

Keep in mind that this is upper has a carbine gas system.

2. Adams Arms Tactical P1/P2/P3 Upper (Mid-Length)

Best Bang-for-Buck Piston Upper
at OpticsPlanet

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons


  • 5.56mm NATO 16″
  • Barrel Material: Chrome Moly Steel
  • 1:7 Twist
  • Muzzle: Pinned A2 Flash Hider
  • Barrel Finish: Melonite / Black Nitride
  • Bolt Carrier: Black Oxide Coated Steel
  • Free Floated Aluminum Forearm
  • M4 Feed Ramps

The Tactical P1/P2/P3 series from Adams Arms is the industry standard for a solid, reliable, piston upper.

Confused on the three options? Basically, P1 is the basic entry tier upper, P2 is more standard, and P3 is upper tier designed for competition or duty carry.

All three are great, but P2/P3 have some extra features such as adjustable gas blocks and such. They also have a higher price to match.

It comes with a very nice aluminum handguard that has a full flat-top rail that connects seamlessly with the rail on top of the upper giving you the ability to mount every kind of sight, scope, laser, can opener, and tactical assault coffee mug your heart desires.

Battle Mug
Battle Mug

Seriously, the rails on this thing (the gun, not the coffee cup) are incredibly functional, and (re)movable so you can place them where you want, or lose them completely for a more high-speed, low-drag look.

Beyond that, the upper functions flawlessly with proper maintenance when used in conjunction with a quality mil-spec lower. It is a bit more expensive than the Stag, but it’s worth it if you have the cash, or want to upgrade a little bit.

Or if you need four lights and a laser to feel safe.  Hey, no judgment here.

Mall Ninja AR-15
Mall Ninja AR-15

Ok…a little judgement.

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…least for my purposes.

Midlength Shooting Target
Midlength Shooting Target

I think the midlength platform is probably the best place to start out for most newbies, and it’s a great starting point for those who just want to try something different as well.

You get a longer forearm than with a carbine length, which makes for an easier shooting experience, but you don’t have too much barrel slowing you down as you do with a rifle length gun.

This is especially an issue when you’re trying to move during a competitive match, a home-defense scenario, or in the confines of a deer stand.

Many a deer has been spooked by a hunter banging their barrel against something in the stand.  No that’s not a euphemism.

3. PWS MK1, MOD 2

Upgrade Piston Upper
at Optics Planet

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons


  • Barrel Length – 14.5″ (Pinned to 16″)
  • Overall Length – 23.4″
  • Gas Piston System – Carbine
  • Barrel Twist – 1:8
  • Caliber- .223 Wylde
  • PicMod Rail System Handguard
  • Forged upper
  • Adjustable Gas Block

If you have the money and want the next level up piston upper, get the PWS MK1, Mod 2

If you don’t have the money and want the very best possible piston upper, get this one anyway.

If the fecal matter has hit the fan, the apocalypse has come, and you’re digging through Rainier’s warehouse to try and build something that will help you survive the wasteland that our world has become, get this one.

Rick Wishes He Had The MK1 Mod 2
Rick Wishes He Had The MK1 Mod 2

Seriously, 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.

This upper has all the features you could possibly want, including the unabashedly cool PicMod System that allows you to use Keymod and Picatinny attachments.

It also has a forged upper receiver, making it stronger and yet lighter than comparable billet receivers.

Finally, it has an easy-to-adjust, low-profile gas block that will allow you to dial down the felt recoil of the gun to get the best possible accuracy and performance possible. This is also key if you’re going to run a suppressor on your gun.

PWS MK1 Mod 2 Complete
PWS MK1 Mod 2 Complete

It’s sitting on top of one of my competition rifles right now, and I have no plans on taking it off anytime soon.

Readers' Ratings

4.99/5 (902)

Your Rating?

4. Barrett REC7 Gen II

Super Upgrade Option
at Euro Optic

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons


  • Barrel Length – 16″
  • Overall Length – 33.25″
  • Gas Piston System – Carbine
  • Barrel Twist – 1:7
  • Caliber- 5.56 NATO
  • Barrett Enhanced Rail with KeyMod
  • Adjustable Gas Block

If you want one of the most expensive piston uppers out there right now…check out the REC7.

While most piston guns don’t really sell their uppers separately…you’re in luck with Barrett.

However, I’d rather have the mid-length gas system and MLOK rails opposed to the carbine gas system and KeyMod.

AR-15 Piston Conversion Kits

Adams Arms Adjustable Gas Piston Kit

(Previous) Editor's Pick Piston Kit
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

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.

I hated all of them but this one.

The Adams Arms Piston Conversion Kit will let you convert your DI upper into a piston upper with a minimum amount of fuss. I love it, and I’ve used two of them now and I couldn’t be happier. I can’t really recommend any other kits in this category because:

A) I haven’t found another one that I like, and…

B) There aren’t really any other ones that are worth your time.

This kit comes with the same adjustable gas block that comes in the Adams Arms upper I told you to buy just a minute ago, and it is altogether the best kit to toss in a mid-length rifle.  They also have kits for rifle and carbine versions as well.

Editor's Pick Piston Kit
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

*Update* Adam’s Arms has their new P-Series piston kit which is MUCH lighter than their previous kit.

I had the chance to shoot it recently and I couldn’t tell that it was a piston conversion since it wasn’t front heavy at all.  My new recommendation for the best adjustable gas piston kit.

Superlative Arms Adjustable Piston Kit

Newer Piston Kit
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

I love Superlative Arm’s adjustable gas block.  In fact…it’s the only one that I use now.  See the full review.

Installed Superlative Adjustable Gas Block on Faxon 14.5 Pencil
Installed Superlative Adjustable Gas Block on Faxon 14.5 Pencil

So I can’t wait to try out their piston system due to their same rave reviews…and how you can easily find the different gas lengths PLUS pencil barrel size in stock.

Stay tuned!

Final Thoughts

That about does it for this one, guys and gals.

Those are my recommendations for choosing a piston based AR-15 upper.

Want a normal DI upper? We’ve got our favorites in our Best AR-15 Upper Assemblies for the Money guide!

Do you use a piston upper? Did you switch back to DI? Let me know in the comments!

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79 Leave a Reply

  • Commenter Avatar

    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.

    July 17, 2022 6:12 am
  • Commenter Avatar
    john carbone

    can i convert a ar 45 gas blowback system with no gas port in the barrel to a piston system

    March 12, 2022 5:42 am
  • Commenter Avatar

    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?

    February 16, 2022 5:53 am
    • Commenter Avatar

      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.

      February 18, 2022 5:28 pm
  • Commenter Avatar
    Nick D'Angelo

    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!

    December 14, 2021 5:50 pm
    • Commenter Avatar
      Jacki Billings, Editor

      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!

      December 15, 2021 1:08 pm
  • Commenter Avatar
    Zach Polson

    I have the mossberg mmr.
    Could anyone tell me if, and what poston System will fit the 16 inch barrel model

    November 12, 2021 11:45 am
  • Commenter Avatar


    Will the Adams Arms Piston Kit (P-Series) work with this



    October 22, 2021 4:41 am
  • Commenter Avatar
    Tim Thoreson

    Will this work in a left handed upper or do they make one for right handed

    June 25, 2021 7:47 pm
    • Commenter Avatar
      Tom Thumb

      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.

      October 20, 2021 2:04 pm
  • Commenter Avatar

    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.

    April 20, 2021 6:13 am
    • Commenter Avatar

      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.

      May 16, 2021 6:02 am
      • Commenter Avatar

        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.

        May 21, 2021 3:13 pm
      • Commenter Avatar

        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.

        June 1, 2021 9:21 pm
  • Commenter Avatar

    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?

    July 10, 2020 10:27 am
    • Commenter Avatar
      David, PPT Editor

      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.

      July 10, 2020 12:20 pm
      • Commenter Avatar

        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.

        May 21, 2021 3:15 pm
  • Commenter Avatar

    Many of the parts on this list are discontinued. I would love to see an updated list.

    May 12, 2020 6:51 pm
  • Commenter Avatar

    Would these work for 300 black?

    April 20, 2020 12:17 am
    • Commenter Avatar

      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

      October 2, 2020 9:11 pm
  • Commenter Avatar

    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.

    January 31, 2020 9:12 pm
    • Commenter Avatar

      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.

      April 19, 2020 7:05 am
  • Commenter Avatar

    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.

    January 9, 2020 11:00 pm
  • Commenter Avatar

    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.

    December 8, 2019 10:26 am
    • Commenter Avatar

      What? Need a hydraulic press to install/remove the AA gas block? Wouldn't that just about eliminate most people?

      May 21, 2021 3:34 pm
  • Commenter Avatar
    Joseph J Guccione

    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.

    December 1, 2019 9:35 pm
  • Commenter Avatar
    Jason Quinones

    Don't drink soda, Ford sucks and wtf is a Goku?

    October 27, 2019 9:38 pm
  • Commenter Avatar
    Eric Wilson

    The Adams Arms conversion works real good and I bought it from Midway before I read your review. Thank you

    August 17, 2019 3:17 pm
  • Commenter Avatar

    should i just get the LWRC piston gun and be done with it??

    May 15, 2019 1:21 pm
    • Commenter Avatar
      Eric Lautz Lautz

      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.

      June 5, 2019 9:09 pm
      • Commenter Avatar
        S. Robles

        I also agree with Eric, I own a few POF’s and very happy with them (you get what you pay for).

        June 22, 2019 11:15 am
      • Commenter Avatar
        Joseph J Guccione

        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?

        December 1, 2019 10:24 pm
  • Commenter Avatar
    Bert Powers

    I prefer shooting and cleaning the gas piston over the direct impingement. The gas piston has a little less recoil too.

    February 10, 2019 2:42 pm
  • Commenter Avatar
    Eric Lautz

    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???

    December 18, 2018 11:24 pm
  • Commenter Avatar
    Cole Warren

    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

    December 12, 2018 6:26 pm
    • Commenter Avatar
      jareth belanger

      Both Superlative Arms and Adams Arms have a diagram for their block dimensions, so look that up and measure your rail. Also on the adams arms you might have to notch the barrel nut on the rail system for the recoil spring so it will sit at milspec length away from the receiver.

      That being said I have shot both and the superlative is the easier to fit one, but the adams arms is more robust. If you are going to be doing fullauto or binary mag dumps, go with the adams. If you just want a piston for cleaning and ease of supressor use, get the superlative.

      December 15, 2018 6:14 pm
  • Commenter Avatar

    I got the same pencil barrel setup for a light weight build (coming from a 16" HBAR). I works great with an Griffin Opitmus on the end - with one huge downside. The 1 pound can causes the barrel to bend 0.006" (6 thousanths) at the gas block and equates to a 3" lower bullet strike at 25 yards. So I will run it unsupressed and get the 11.5" mid-length gas Faxon Gunner barrel that is stiff and designed for dedicated suppressor use.

    October 24, 2018 6:32 pm
  • Commenter Avatar

    I know this is a dead thread by now, but that Superlative piston system is the best IMO. I think in another year after it's been compared to the rest by all the gurus out there that it will rise to the top of the list. Several enlisted gear heads I know swear it's a much better designed system than the other piston kits like apples and oranges and I agree. Maybe others will pip in and add to that testimony ?

    October 24, 2018 4:33 am
    • Commenter Avatar
      jareth belanger

      I did a 10 (30rd) mag dump through it with a binary trigger and a shot timer with around 670rpm per mag and ~2 sec mag changes on a shot timer, estimated because on mag 6 it seized. I melted the recoil spring inside the housing and mushroomed the bottom of the piston in the housing because of that, had to drive the piston out with a hammer after it was pulled off the barrel.

      That being said, 99% of people will not torture their rifle like that. But if heat absorption is an issue. I would go adams arms over the superlative, even with the barrel nut fitment issues. But for general suppressor or range use the superlative will work fine. Also on my kit they packaged the wrong diameter block, and wouldn't get back to me. Luckily I bought it from brownells and explained the issue and they gladly swapped it for me. So another thing to keep in mind.

      December 15, 2018 6:22 pm
  • Commenter Avatar
    Richard Stanley

    Your article is full of inaccuracies. It’s common knowledge the correct answers are Pepsi, Chevy, and Superman. Goku shouldn’t even be a choice, Batman for the win. As far as the gun stuff goes, good article. I enjoyed it.

    October 3, 2018 6:17 pm
    • Commenter Avatar
      Anthony Gonzales

      Agree, agree, and you couldnt be more wrong about Goku. If you knew even the slightest amount of dragon ball super, you wouldn't go spouting off about a buff dude with a fat bank account and a utility belt lmao. Goku is basically a God and superman can be snuffed out with a wee lito bit of kryptonite. ..

      October 11, 2018 3:07 pm
  • Commenter Avatar

    I have experience with the Adams Arms mid-length upper and the Superlative Arms conversion kit. i both systems in operation. I use both AR15s in carbine and two-gun matches. Both options are reliable and keep the receiver clean. Both guns operate without malfunction or misfeed given good magazines.

    The Adams Arms upper is durable. The upper has years of use and many thousands of rounds through it. In fact, I amreplacing the barrel. Yes, Melonite-treated barrels wear out after a respectable number of rounds. My only criticism is handguard heating. The Adams Arms gas block exhausts gases at the rear of the block. The handguard gets hot after 100 rounds. This is a small criticism. All guns get hot after enough rapid fire.

    The Superlative Arms conversion kit is added to a Faxon mid-length 16 inch barrel and Faxon upper receiver. It was easy to assemble with the right tools. The instructions were clear and accurate. I have several hundred rounds through the Superlative Arms system.

    There are no instructions regarding cleaning the Superlative Arms gas block and no mention of a requirement to clean the gas block. I have not cleaned or lubricated the gas block since it installation. It functions and feeds flawlessly. It is lighter than the Adams Arms, especially out front. The gas block exhausts gas out of the front toward the muzzle. The handguard stays cool a little longer. I need more rounds through the gun to determine the conversion kit durability and the need, if any, to clean or lubricate the gas block.

    September 5, 2018 6:24 pm
  • Commenter Avatar

    Swapping the carrier rather.

    May 2, 2018 10:22 am
  • Commenter Avatar

    I’m interested in building a side charging piston driven 7.62x39 upper. Any input would be great. I’ve found side charging DI uppers but not the combo of side charging/piston. Would it just be a matter of swapping the gas key for its piston counterpart?

    May 2, 2018 5:06 am
  • Commenter Avatar

    Haven't seen too much online about the Superlative arms kit. I know its compatible with quite a few more handguards as it doesn't need a standard milspec barrel nut. I'm building a 11.5" pistol with intentions to run it suppressed 90% of the time. Would you recommend the Superlative system over the AA? There just isn't too much 3rd party info out there on the superlative arms system. The review link for superlative isn't active btw.

    March 30, 2018 12:49 pm
  • Commenter Avatar

    So does the Adams Arms Piston Kit (P series) work with the Superlative Adjustable Gas Block?

    March 26, 2018 5:50 pm
    • Commenter Avatar
      Matthew Collins

      I'm not sure. I'd pick up a P series gas block from AA, if one isn't included in the conversion kit.

      March 26, 2018 9:11 pm
    • Commenter Avatar

      You can't use the AA and Superlative parts together 2 different set ups. The AA has a different style of op rod with the spring against the barrel nut vs the Superlative being contained in the adjustable gas block.
      So the 2 are different in that aspect.

      As far as one being better than the other again is users choice, would you rather have a spring at the barrel nut or in the gas block..
      I have the Superlative adjustable on a 14.7 Hanson profile BA barrel fitted to a Aero Precision upper with a Vltor Flash hider, I get zero gas back in my face and all the excess gas is adjusted out the front of the Superlative gas block.

      This was my first build and I have a approximately 200 rounds through it so far, Once you set you the gas block per the directions and follow the adjustments you can dial in the gas venting to your desires=d style and preferences.
      Well worth the $260 for the Superlative piston kit which included the bolt carrier minus bolt,

      August 18, 2018 8:46 pm
  • Commenter Avatar

    Coke, ford and goku...done. Go buy a noveske for my first plinkin rifle? Whatever you say

    March 5, 2018 1:20 am
  • Commenter Avatar
    Hairy Johnson

    I have the Barrett Rec7 Gen2 piston and its my favorite AR I've had to date and I've had a LOT of top shelf AR's. I also own an LMT piston AR and its my second favorite. It's a close second! But I've owned POF (great gun too) LWRC (didn't like, not reliable) Sig 516 (decent) and a Ruger 556 piston (SUCKED).. Those are just the piston models I've owned. I definately love the Barrett Rec7 Gen2 the most! The LMT is for sure the second best I've ever used or owned. POF is great too (just couldn't get used to the damn gigantic and colossal handguard) but the rest are not worth the money. I've never shot a PWS piston AR but I've heard good things about them. Anybody that wants the best regardless of price should get the Barrett. And they now come with an M-Lok handguard (Damnit mine has keymod!). My DI guns I own are 2 Daniel Defense rifles and Knights Armament..... And its, Pepsi-Ford-Superman.

    February 27, 2018 5:20 pm
  • Commenter Avatar

    Currently at the moment I own two gas piston AR style guns. One is an LWRC M6 A2 SPR & a Hogan. Both are Fantastic but the Hogan just shoots like no other. There is virtually no recoil with the Hogan as it feels like you're shooting a .22 lr but on the other hand this thing is EXTREMLY loud. POF is another great manufacture of gas piston driven weapons... Just a FYI...

    February 17, 2018 3:15 pm
  • Commenter Avatar

    I have an Adam's Arms Tac Evo with a kryptex finish. It was my first AR and while I was going for a Sig M400, the Sig was out of my price range. The salesman showed me the AA TEvo saying it had just as good of components at a better price. I wanted to get a fully set up AR for under $1k. The AA came in at $950 (WA), felt great and seemed smooth. I put a Vortex Strike Eagle on it and am totally in love with the AA. It's lighter than the S&W MP (my other contender). and came with all of the extras.
    I will probably build my next AR. And I would like to add a special "Thanks" to the Pew Crew for all of the invaluable information. Your research has answered a lot of questions and my education wouldn't be as complete without all of your insight. Again THANK YOU!!!

    December 18, 2017 1:06 pm
    • Commenter Avatar
      Eric Hung

      So glad we could help out, Matt. Let us know how your next AR build goes!

      December 18, 2017 7:51 pm
  • Commenter Avatar

    Great comparison I have a pws DI 14 inch upper only dont live in a free state.
    just ordered a mk118 mod2 cant wait.
    and its coke, chevy & superman.

    November 29, 2017 7:19 am
    • Commenter Avatar
      Eric Hung

      Thanks Steve, let us know how it's running!

      December 14, 2017 12:41 pm
  • Commenter Avatar
    Al abotheguns

    2 out of three not bad.... Chevy takes the lead with small blocks and LS series motors. Good info and well done.

    November 7, 2017 5:07 pm
  • Commenter Avatar
    Ryan Phillips

    Piston AR's and no mention of Patriot ordnance firearms? I feel they have really led the market in new innovations for piston ar's. One of few who did a 7.62x39 piston ar fully reliable out of the box too! Love my POF 300 Winchester Magnum AR10. They even make a ar15 .308 now. This has been on the cover of every gun magazine out lately.

    October 16, 2017 11:07 am
    • Commenter Avatar

      308 means its an AR-10 not AR-15. but POF does make some great gear.

      March 8, 2018 7:07 pm
  • Commenter Avatar
    Casey Plunkett

    At one time I had an LWRC, short stroke piston, and a PWS, long stroke piston. Eventually I sold the LWRC as thej PWS(mk116) was more accurate
    and overall more enjoyable to shoot. Customer service and tech support with piston guns is very important as mentioned in the article and let's just say one was top notch with the other was completely unresponsive. I know own the mk116 mod1, a mk114 mod2 and mk220 6.5creedmoor.
    Just a quick, subjective, observation on how short stroke-tappet operation and long stroke piston systems compare: the stroke stroke has an abrupt snappy recoil where as long stroke has a smoother, albeit stronger than DI, push effect. Some, myself, include feels the recoil from Long Stroke allows for quicker more accurate follow up shots. The fact that PWS rifle can be seen used in 3 gun and other competitive circuits whereas I can't think of anyone using short stroke rifles competively would attest to that.

    October 15, 2017 9:42 pm
  • Commenter Avatar

    Has anyone built or reviewed a piston SBR? Can you run a piston on say an 8"-10.5" in .300 AAC with suppressor? Sounds like a research project for pew-pew...

    October 15, 2017 8:48 pm
    • Commenter Avatar
      Eric Hung

      Good idea, Andrew!

      October 17, 2017 3:34 pm
      • Commenter Avatar

        No mention of the HK MR556 upper? I heard it's required to use a tall hammer with the HK MR556 upper before it be works properly.

        December 6, 2017 10:32 pm
  • Commenter Avatar
    Kevin Buenafe

    I love piston guns. They run super clean. The upper receiver isn't on fire after you rapid fire 50+ rounds. Bolt carrier almost never needs to be cleaned, just the bolt itself. The only tricky part is finding handguards that work with piston systems. They're all designed for DI. But some do work and some of the better uppers come with decent hand guards. I have a Black Rifle Arms piston upper and I love it. Comes with Troy M-lok rail. My next piston gun will be an Adcor side charging AR15.

    October 15, 2017 3:34 pm
  • Commenter Avatar

    RC, Jeep, and Sentry!
    Okay for a pistol AR with 7.5 barrel. Piston is the way to go? especially if I want to suppress it...you know after eating roman and tuna for a year to save the money.

    October 8, 2017 8:06 am
  • Commenter Avatar

    Do you need a different upper if your building a piston AR or will any direct impingement upper work as well?

    October 3, 2017 4:58 am
    • Commenter Avatar
      Eric Hung

      The upper receiver can stay the same.

      October 3, 2017 2:57 pm
  • Commenter Avatar

    I think piston is the way to go , patriot ordnance or adam arms?....mmmnnn......

    Another benefit to look at is avoiding all the exhaust blowback from the rifle. According to the diagram, the exhaust is going forward, instead in your face.....

    Anyhow, I think piston is the way to go , patriot ordnance or adam arms?....mmmnnn......

    May 11, 2017 9:41 pm
  • Commenter Avatar

    I have a PWS MK216 in .308 with a long-stroke piston and it is an absolute dream to shoot. I would concur that the PWS is a top-notch AR platform in any caliber offered.

    April 12, 2017 2:18 pm
    • Commenter Avatar

      100% agree. I looked at everything for my .308, DD, POF, LaRue, Barrett, FN, and settled on the PWS long stroke piston, absolute phenomenal shooter. The only upgrades I will do is the stock and grip, l;ikely drop in a Geissle trigger, and add a TBAC can to the front. These are absolutely not required, put decent glass on it, run some quality handloads, and you will easily be sub-MOA. Love my PWS.

      October 15, 2017 8:45 pm
  • Commenter Avatar
    Ben Bruinius

    Coke Ford And Superman are the correct answers

    March 30, 2017 5:21 am
    • Commenter Avatar
      Viet Luu

      I agree with the first 2 but, Goku > Superman. Haha.

      March 30, 2017 11:00 am
  • Commenter Avatar
    Jim M.

    When converting from D.I. to piston, have you noticed any impact on tuning or does the piston system run pretty comparable? Also, being that there are moving parts more forward in the rifle, is this noticed during shooting? It seems like the barrel would "dip" when the piston resets. Great article, but it's Coke, Ford, Superman, probably 'cuz I'm old!

    March 30, 2017 3:06 am
  • Commenter Avatar

    Anderson RF85 treated uppers are a little cheaper and really work...

    March 30, 2017 1:37 am
  • Commenter Avatar

    got an ospry piston and love it, much cheaper too

    March 29, 2017 11:12 pm
  • Commenter Avatar
    Victor Corral

    Great article. On the piston conversion kits, did you try the Superlative Arms conversion kit? If so, how does it stack up to your pick, the Adams Arms conversion kit?

    March 29, 2017 9:52 pm
    • Commenter Avatar
      Eric Hung

      I dig the superlative arms gas block but haven't had the chance to use their piston conversion kit yet.

      April 5, 2017 4:33 pm
  • Commenter Avatar

    I did t see LWRCI's piston rifles on this list. Do they under perform in comparison?

    March 29, 2017 8:17 pm
    • Commenter Avatar
      Eric Hung

      They are a great company we just haven't had that much experience with them.

      April 5, 2017 4:32 pm
  • Commenter Avatar
    Harv M

    Very interesting article. I already have a carbine so I'd like a longer length barrel for distance. Does the Adams Arms (or any other reputable manufacturer) make a piston upper with an 18" or 20" barrel?

    March 29, 2017 5:59 pm
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