Piston or Stoner?

[Strangedays]

I am doing a build and trying to figure if I want to go with an Adams Piston kit or just run it the dirty stoner system?
Is there anything that could lead to accuracy loss with the piston on a free floated barrel or would it be the same as the gas tube? I was thinking of going with a WOA 16" match barrel with bolt. Thanks ahead of time.

 

[K_4c]

Re: Piston or Stoner?

i don't care what anyone says (haha) a well made piston set up will run with DI's... my LWRC M6A2&3 do just fine... and I don't have to jack around with cleaning. I would go as far as to say that its got the best of the AR and the AK (reliable)... Let us know what you decide. I was thinking about getting my M6A2 rebarrled maybe even dimple or swirl flute it as well.

 

[TheRifleman]

Re: Piston or Stoner?

Some piston systems have worked to improve inherent loss of accuracy, and succeeded. That said, a piston gas gun will not be as accurate as direct impingement.

 

[jmrehan]

Re: Piston or Stoner?

I posted this elsewhere. Just my .02.

I HAD an adams arms piston kit. Installed by adams arms, and snapped 3 pistons. Kept sending the upper back and forth. After 3 pistons, despite good customer service, I said screw this, switched back to DI, and now have a reliable stoner designed rifle again. Too bad the thing chewed the crap out of my brand new upper even WITH a one piece bolt carrier that "prevents" carrier tilt. That's my mileage, your's may vary. I will never piss on stoner's grave again.

Also: ruined my mil-spec charging handle, one buffer tube, chewed up a second, chewed up the buffer area of the lower, created cam-pin drag (bolt spring supposed to prevent) lots of marks inside upper where cam pin dragged and inside the CH sliding area.

 

[jmrehan]

Re: Piston or Stoner?

I will say though that the thing ran damn clean, still grouped moa with a piston snapped in 5 places. I think the idea of a retrofit piston kit will almost never work, but uppers that are redesigned to work around the piston system are the way to go. sig, h und k, lwrc and such. I believe those systems will work 100x better than the AA, CMMG, opsrey or what-have-you retrofits. again, just my .02.

 

[USMCj]

Re: Piston or Stoner?

Out of all the piston designs, the PWS short strok is my favorite. Have not noticed any accuracy lose, and it has been very reliable. Look up ADDAX TACTICAL, they use the PWS system in their GPU (Gas Piston Upper) and they do a great job making sure it functions 100% before leaving the shop.

 

[oneshot onekill]

Re: Piston or Stoner?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jeff rehan</div><div class="ubbcode-body">I posted this elsewhere. Just my .02.

I HAD an adams arms piston kit. Installed by adams arms, and snapped 3 pistons. Kept sending the upper back and forth. After 3 pistons, despite good customer service, I said screw this, switched back to DI, and now have a reliable stoner designed rifle again. Too bad the thing chewed the crap out of my brand new upper even WITH a one piece bolt carrier that "prevents" carrier tilt. That's my mileage, your's may vary. I will never piss on stoner's grave again.

Also: ruined my mil-spec charging handle, one buffer tube, chewed up a second, chewed up the buffer area of the lower, created cam-pin drag (bolt spring supposed to prevent) lots of marks inside upper where cam pin dragged and inside the CH sliding area. </div></div>

This whole post IS BULLSHIT! I'd like to see a "broken Adams Arms Piston". Let alone 3 of them!!! You're so full of shit I can hardly stand it!!!

Being "one-piece" is NOT how the BC reduces Carrier tilt. And carrier tilt DOES NOT damage your upper!!! Moron!!! It's the shape of the back of the BC that reduces carrier tilt. Making it one-piece prevents the piston rod from loosening the part that replaces your carrier key on the cheaper system that enables you to use your existing BC.

There are rifles that have run TENS OF THOUSANDS of rounds with very little carrier tilt evidence and in ALL cases it ceases after a certain number of rounds because it's worn as much as it can... and none of these cases have caused a failure of the Buffer tube! Chewed up the buffer area of the lower??? Please...

I can't even comment on any more of this! There's so much mis-information here... Whoever you are you obviously have NO personal experience with Piston AR's so please just SHUT THE FUCK UP!!!


End of rant...

 

[Powder_Burns]

Re: Piston or Stoner?

DI gun still weighs less and has less parts to break.

 

[Guest]

Re: Piston or Stoner?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tort1</div><div class="ubbcode-body">Some piston systems have worked to improve inherent loss of accuracy, and succeeded. That said, a piston gas gun will not be as accurate as direct impingement. </div></div>

This statement makes no sense......."I award you no points, and may God have mercy on your soul." I will try to expound on what I think you might be trying to say.

The 416 and LWRC, which I and a fellow teammate respectively run are 2 of the finest stock AR's that money can buy. Why? Because they are complete systems built with quality components to specifications. All of this piston inaccuracy stuff is coming from one of 2 places:

1) After-market drop in garbage that is geared to make gun monkey mall ninja feel that much cooler at the range a.k.a Scooter's back 40. Either that, or those people that want to be condescending at the range, "No, Harvey it's piston driven, gas impingement is so 90's"

2) Gun duffers that bitch that the increase in recoil is hindering their accuracy. If these people played golf, they would blame a 2mph cross wind for the reason they just sliced the ball 300 yards across the 2 neighboring fairways. Pay no attention to the man with no fundamentals!!!


Am I a piston snob? No. Do I think it is a good idea? Yes.. if done properly. The ugly truth is that the folks that would truly benefit from a good piston system will never get it.....those deployed overseas; government contract has seen that it won't happen any time soon.

I still stand by the fact that a DI gun will work for 99% of those using AR's domestically. That being said, one needs to know the basic operating and maintenance needs of our guns. Fancy gadgets and drop in parts aren't going to be replacing solvents and oils for many many years.

 

[K_4c]

Re: Piston or Stoner?

well put Pointblank4445.

 

[oneshot onekill]

Re: Piston or Stoner?

It may not sound like it but I have no real preference either way. However, I have studied piston AR's extensively and shot most of them. I have to agree the drop-in systems are not as well engineered as the ones designed into the rifle from the start but Adams is one of the better ones.

 

[ORD]

Re: Piston or Stoner?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: M24kinnamon_4c</div><div class="ubbcode-body">well put Pointblank4445. </div></div>

Amen, and AMEN!! You are right on the money, Pointblank!

 

[BugSniper]

Re: Piston or Stoner?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pointblank4445</div><div class="ubbcode-body">
The 416 and LWRC, which I and a fellow teammate respectively run are 2 of the finest stock AR's that money can buy. Why? Because they are complete systems built with quality components to specifications. All of this piston inaccuracy stuff is coming from one of 2 places:
</div></div>

Excuse my ignorance, but where is the bullet when the piston moves on these piston systems? Does it vary by manufacturer?

I can't believe that on the smallest scale there is no difference between a piston impact and blowing on the bolt. I have no idea which would be better and suspect the variation it is far, far smaller than bullet margin of error, but they are clearly different as one has one body moving where the other has a small body colliding with a larger one, so they shouldn't behave exactly the same.

Depending on the bullet location, I would expect the gas buildup in a piston system to be more consistent than in a DI system with loose tolerances and seals.

 

[Guest]

Re: Piston or Stoner?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BugSniper</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pointblank4445</div><div class="ubbcode-body">
The 416 and LWRC, which I and a fellow teammate respectively run are 2 of the finest stock AR's that money can buy. Why? Because they are complete systems built with quality components to specifications. All of this piston inaccuracy stuff is coming from one of 2 places:
</div></div>

Excuse my ignorance, but where is the bullet when the piston moves on these piston systems? Does it vary by manufacturer?

I can't believe that on the smallest scale there is no difference between a piston impact and blowing on the bolt. I have no idea which would be better and suspect the variation it is far, far smaller than bullet margin of error, but they are clearly different as one has one body moving where the other has a small body colliding with a larger one, so they shouldn't behave exactly the same.

Depending on the bullet location, I would expect the gas buildup in a piston system to be more consistent than in a DI system with loose tolerances and seals.

</div></div>

You are right that they are totally different animals. The buffer and recoil spring required for my 416 requires 2x the effort to charge the gun vs. my DI guns. The bolt and carrier are noticeably bulkier and recoil is stiffer. However my accuracy is equal to or better the 14.5" Colt socom upper it replaced.

As per your fist question, I can't tell you for sure. And I can't really say how much this depends on the barrel length either.


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Powder Burns</div><div class="ubbcode-body">DI gun still weighs less and has less parts to break. </div></div>

Ya know, I sang this tune before I got my 416 upper. You are right about the weight, but I am running a heavy profile barrel too. But concerning the parts increase, this is BS (at least in my gun).

Consider this, what is added?
Piston, op rod, spring

Consider what is replaced
Gas key, gas key screws (and the need to stake them), gas tube, gas tube roll pin

And the gas rings are moved from the bolt to the piston.

I consider it a wash if not in increase in more robust parts. And if anything what you are removing from the equation is heat.
What damages things:
wear and tear (increases with lack of lube)
lack of lube (loss increases with heat/use/dirt)
heat (puts added element of stress on metal

So, on a basic level, most of all mechanical failures (not contributed to human error) can be linked back to either time (use/age) or heat.

Your barrel is gonna get hot.....period. And I know a few of the piston manufacturers have acknowledged and allowed for this concerning the relative proximity of the op rod in relation to the barrel. But what about in the upper receiver? You are saving yourself a lot of trouble by directing that heat away from your bolt group. We've all seen the HK demo of the guy doing a mag dump and pulling out the bolt and holding it in his hand. It's not BS. Try it with your DI....see what happens.

 

[scotharr]

Re: Piston or Stoner?

To do a piston right, you need to have the BCG fixed to a rail because the piston hits it off-center. The original Stoner design blows the BCG straight back without any cant. Translation: piston modifications of the AR design are inherently flawed. Go with a piston that was designed to be a piston from the beginning. The stoner DI design has been around for decades and has proved to be extremely reliable except when you make the barrel(and DI system) too short: anything 14.7" or less, or when you use a suppressor. 16"-20"+ DI systems work great, with full-length systems(18-20" barrels) being the best. I tried The Adams kit and sent it back: didn't add any value to a 20" AR.

 

[Rotortuner]

Re: Piston or Stoner?

I would only do a piston if your going to use a supresssor. that is pretty much the only time you really take advantage of the piston setup. Otherwise its just more complicated.

CJG

 

[Strangedays]

Re: Piston or Stoner?

I decided not to go with a aftermarket piston and use the great same setup I have on all my guns, DI. Maybe in the future I will pick up a LMT piston upper but for right now I am going to run the DI on my new build. Thanks for all the input, this site is great on helping a person make their mind up or worse give to many options leaving your head swimming.

 

[jmrehan]

Re: Piston or Stoner?

One shot, PM sent. If you think so highly of piston's you can buy my kit and get snap happy. I have the gas block # and RMA's numbers, tracking information, and gunsmith invoices from adams arms stating what they believe happened, what they tried to fix it. I give two shits if you want to suck on the almighty dick of piston kits, but I have snapped three.

 

[396chevy]

Re: Piston or Stoner?

OK Jeff did you follow the directions? What ammo were you using? Because the only way I could ever see a piston snapping is it hitting something{IE not installed correctly} or using extremely hot rounds, maby hot 556 nato in a 223rem chamber?? But the second possible reason is a very far stretch.We would also like to see pics of all this damage. As I am very curious how a piston upper can cause the damage you say it did. Oh and those of you saying that it is less reliable with more parts all I can say is WTF?!?!?!?! {refer to pointblank4445's posts for more info} I would highly recommend a piston complete upper, personally I would stay away from the add on kits. Advantages or a piston upper, Enhanced reliability, reduced wear on all parts upper and lower. Disadvantages slightly increased recoil, heavier, and some find it bulky. I ask have any of you seen a 9mm AR's lower after a few thousand rounds with out cleaning? Its almost as clean as it was when it was new.

 

[396chevy]

Re: Piston or Stoner?

And Jeff you joined September 1st of 09 and you haven't filled out your profile and have only made 9 posts {3 of which were on this thread} I ask why did you join? At this point I'm not entirely sure of your intentions but they are not looking honorable.... Please prove me wrong.

 

[jmrehan]

Re: Piston or Stoner?

Ok well sorry I didnt fill out my profile. I joined to look at some forums and buy some glass off someone mainly, ill make sure to fill it out at some point.

All ammo was factory xm193 or m855, shot from a sitting bench, slow fire, zeroing an eotech and for groups at 50m. The upper was CMMG. I will try to find pics, but seriously, I left my external hard drive behind on my last deployment and I think it had the pics. another member who i shoot with is on this site and i will ask him to confirm as he was at the range with me.

About me and my intentions: I spent 3 yrs active army infantry, in B co, 1-22 infantry, 4th ID, stationed at ft. hood. I spent time I Iraq as both a mounted and dismounted infantryman in a mechanized battalion, but I am in the Chair force now. We saw a good deal of action, and my life relied on my m16a4, with DI. After dealing with the fouling and sand and bullshit for years, I wanted a piston kit. I bought the AA kit back when it was $500, and the one piece bolt carrier was $200.

There was no sideways pressure on the piston, it sat under a daniel defense omega rail, and did not touch anywhere. The carrier tilt i speak of, was obvious where on the opening of the buffer tube, and the treaded area around there. the one piece bolt carrier has a thick and strongly made strike face, with would drag along the inside of the CH. at the rearmost position it would dig into the CH groove, and also dig in at the front. the cam pin drag i saw, (which i still have the upper, so i will take pics of these wear areas with my cell) was in cam pin recess area and just around it, where the finish and some metal has been obviously removed. I would find shavings in my lower receiver after shooting.

If theres anything else you guys would like to know ill answer questions. my intentions arent malicious, i dont want to snub AA. maybe their kit is just not compatible with CMMG uppers, and CMMG may have machined their flash hole that way so they would only be used with their kit. I have no idea. I just know I would like to see another CMMG Bbl run an AA kit. Adams Arms customer service was top notch throughout it all. I truly appreciate how they helped me out but jesus, after three tries I think all of you guys would want to go back to ol' reliable that you have put your life on the line with right? i dunno, maybe im nuts but after it is all said and done I know I can rely on my rifle now. Let me know if i still sound like a crazy asshole.

 

[jmrehan]

Re: Piston or Stoner?

one shot, thanks for the apology, your a pretty decent dude after all. and the bushing in the upper was installed correctly, hell, adams arms had my rifle 3 times.

 

[K_4c]

Re: Piston or Stoner?

Got roughly 2k through my LWRC M6A2... no problems to date. I served as well bud... nite and day differnce in reliablity (colt DI v.s LWRC Piston). Sucks your kit (AA kit) had it's issues...

 

[396chevy]

Re: Piston or Stoner?

Well it looks like I put my foot in my mouth again. And I am happy to say that you proved me wrong. I apologize sincerely Pat

 

[oneshot onekill]

Re: Piston or Stoner?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jeff rehan</div><div class="ubbcode-body">one shot, thanks for the apology, your a pretty decent dude after all. and the bushing in the upper was installed correctly, hell, adams arms had my rifle 3 times. </div></div>
No problem. It was wrong of me to go off on you that badly. I'm still baffled about your problems and would like to see pictures. I'm a little surprised Adams didn't do more for you if their system damaged your rifle.

 

[Q-01]

Re: Piston or Stoner?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BugSniper</div><div class="ubbcode-body">
Excuse my ignorance, but where is the bullet when the piston moves on these piston systems? Does it vary by manufacturer?

I can't believe that on the smallest scale there is no difference between a piston impact and blowing on the bolt. I have no idea which would be better and suspect the variation it is far, far smaller than bullet margin of error, but they are clearly different as one has one body moving where the other has a small body colliding with a larger one, so they shouldn't behave exactly the same.

Depending on the bullet location, I would expect the gas buildup in a piston system to be more consistent than in a DI system with loose tolerances and seals.

</div></div>

Speaking to the LWRC system, which I shoot, here are quotes from two guys who have probably run more rounds through LWRCs than anyone else I know.

"The piston is not in operation until the bullet is clear of the crown. By the time the piston cup has filled to enough pressure to over ride that oprod spring and action spring, the cup is no longer contacting the gas nozzle. The barrel can continue through its whip cycle without being contacted by the recoil system. however, DI guns are tied in with a gastube... Just throwing that out there.

Accuracy comes from trued recoil bearing interfaces (perpendicular to the centerline of the bore), and rigidity of the action. " - borebrush

"I don't know about other short stroke piston operated carbines, but the cycling of the LWRCi gas piston system has zero effect on practical accuracy. I have confirmed this time and again by shooting my M6A3 in the various gas settings (including "O" off) for accuracy (off a bipod in prone position at 100 meters). There is no significant difference to the group sizes." - Stephen

HTH,

Q001

 

[Sierra Bravo]

Re: Piston or Stoner?

I have the Adam's set-up on my AR. I've never even heard of anyone breaking their gear. Moreover, I put up .82" group up the other day in a downpour. I would say the piston system didn't effect accuracy in the least.