Piston AR, best accuracy?

yohann160 said:
No piston AR justifies the price difference. It's a gimmick like nickel boron bolts to attract people with shiny or sparkling new parts. If you want a piston gun there are far better options than a poorly/lazily engineered retrofit piston AR.
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PWS is not a retrofit. Which ones are you talking about?
Might not justify the price for you but I sure am happy with both my PWS AR's, my 223 has over 4000 rounds through it without a single broken or worn out part and no failures to feed, extract, or fire that weren't caused buy the operator not seating the mag fully. It is also capable of sub moa groups at 100yds with good ammo.
I don't really think it's a gimmick but they are solving a problem that wasn't really there to begin with. It's just another way to do the same job.
The thing I like most about my piston rifles is that there is no gasses blowing in your face when you shoot, all venting is done under the hand guard away from your face.
 
cr5 said:
PWS is not a retrofit. Which ones are you talking about?
Might not justify the price for you but I sure am happy with both my PWS AR's, my 223 has over 4000 rounds through it without a single broken or worn out part and no failures to feed, extract, or fire that weren't caused buy the operator not seating the mag fully. It is also capable of sub moa groups at 100yds with good ammo.
I don't really think it's a gimmick but they are solving a problem that wasn't really there to begin with. It's just another way to do the same job.
The thing I like most about my piston rifles is that there is no gasses blowing in your face when you shoot, all venting is done under the hand guard away from your face.
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My instinct is to be Alexandrian, that is why I prefer to solve a difficult tangle with one sharp, clean stroke. Which brings me to the Stoner AR15 design. DI does the job with less parts and less weight. The rest is just a sales pitch. Can't blame the manufacturers because all they do is respond to a demand in a market filled with gullable people who don't quite understand how the Stoner AR15 actually works. They are all retrofit, IMO, because they all add unecessary parts to a design that has worked fine for half a century. Speaking of carbon blowback to your face, you should read KevinB's take on the merits of DI and piston on suppressed rifles. Interesting food for thought.

Gunnerlove: I should've been more precise, I mean the locking lugs in the chamber. One drop of FC on the bolt lugs and one drop on the barrel extension locking lugs.

Try dropping some lube through the two vent holes and into the expansion chamber/gas rings area next time you have problems at the range. Or take the bolt out of the gun and drop it in a pale of WD30 and see if that fixes the problem.

When I get home I'm going to find that video of LAV dropping his DD in a bath of motor oil and embed it here.
 
yohann160 said:
My instinct is to be Alexandrian, that is why I prefer to solve a difficult tangle with one sharp, clean stroke. Which brings me to the Stoner AR15 design. DI does the job with less parts and less weight. The rest is just a sales pitch. Can't blame the manufacturers because all they do is respond to a demand in a market filled with gullable people who don't quite understand how the Stoner AR15 actually works. They are all retrofit, IMO, because they all add unecessary parts to a design that has worked fine for half a century. Speaking of carbon blowback to your face, you should read KevinB's take on the merits of DI and piston on suppressed rifles. Interesting food for thought.

Gunnerlove: I should've been more precise, I mean the locking lugs in the chamber. One drop of FC on the bolt lugs and one drop on the barrel extension locking lugs.

Try dropping some lube through the two vent holes and into the expansion chamber/gas rings area next time you have problems at the range. Or take the bolt out of the gun and drop it in a pale of WD30 and see if that fixes the problem.

When I get home I'm going to find that video of LAV dropping his DD in a bath of motor oil and embed it here.
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We dont have suppressor problem solved and the fact alone gas isnt coming to my face and that I dont have to clean often the gas tube was a huge factor for me. When im shooting the DI ar15 of my father I hate the gas on my face and it smell toxic. About the more weight and the more parts, I dont care because I bought a quality AR15 from pws and it is lightweight and reliable
 
PoFF said:
Ammunition is my reloaded match ammo using 75 grains bullets (so 1-8 twist minimum, 1-7 optimal
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Just a note on twist rates and AR's, but a 1/7 twist is completely unnecessary in a rifle that isn't shooting the U.S. Issue super long tracers. A 1/8 will stabilize up to 80gr VLD's, which are about as long as you can seat in a round feeding from an AR magazine.
 
charlesquik said:
We dont have suppressor problem solved and the fact alone gas isnt coming to my face and that I dont have to clean often the gas tube was a huge factor for me. When im shooting the DI ar15 of my father I hate the gas on my face and it smell toxic. About the more weight and the more parts, I dont care because I bought a quality AR15 from pws and it is lightweight and reliable
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Umm, you never need to clean a gas tube, never ever.
 
yohann160 said:
My instinct is to be Alexandrian, that is why I prefer to solve a difficult tangle with one sharp, clean stroke. Which brings me to the Stoner AR15 design. DI does the job with less parts and less weight. The rest is just a sales pitch. Can't blame the manufacturers because all they do is respond to a demand in a market filled with gullable people who don't quite understand how the Stoner AR15 actually works. They are all retrofit, IMO, because they all add unecessary parts to a design that has worked fine for half a century. Speaking of carbon blowback to your face, you should read KevinB's take on the merits of DI and piston on suppressed rifles. Interesting food for thought.

Gunnerlove: I should've been more precise, I mean the locking lugs in the chamber. One drop of FC on the bolt lugs and one drop on the barrel extension locking lugs.

Try dropping some lube through the two vent holes and into the expansion chamber/gas rings area next time you have problems at the range. Or take the bolt out of the gun and drop it in a pale of WD30 and see if that fixes the problem.

When I get home I'm going to find that video of LAV dropping his DD in a bath of motor oil and embed it here.
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Like I said, the piston AR solves a problem that wasn't there in the first place. We agree on that point.
The DI system is a great system and is a piston rifle, an internal piston system, I understand exactly how it works, which is why I own both types of AR's.
Even Eugene himself must have seen advantages in the external piston design though, why else would he have designed the AR-18 as a replacement for the AR-15? It probably would have taken off but the US military had already spent too much money on the AR-15 platform to consider switching over.
It's nice to have options though and the external piston system does have a couple advantages. Weight and increased part count are not advantages of the external piston operated rifle but it isn't enough of a drawback to care about as a civilian recreational shooter. I don't shoot enough in a day to actually worry about one running cleaner than the other and as for heat build up the DI rifle BCG and upper receiver get a little warmer but on a piston rifle the forend seems to get warmer.
I couldn't care less about Kevin's take on suppressed rifles. I'm not allowed to own a suppressor and I've only ever shot 1 rifle with a suppressor so it doesn't apply to me in the least. Doesn't apply to 90% of Canadian shooters so who really cares?
As for accuracy, well the DI system has more potential but if comparing two high end AR's the difference is slight. My 12 inch PWS can shoot sub moa and as far as I'm concerned that is more than good enough for anything an AR will be used for.
 
mikethebike said:
yes a 5 inch group at 500 is a whole lot different than a 1 inch group at 100, even though they are both 1 moa, i think pretty much anyone that has shot past 200 yards understands that.
but we're just talking the rifle's aptitude here, not the shooter...
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I too am referring to the rifles' ability. There are more than a few rifles out there that can easily hold moa with a small group out to short distance, but as that distance increases the accuracy falls off exponentially.

PoFF said:
Might be the powder, I'm loading with H4895, which is not technically ideal for 223 Rem, but it's been the only powder I could find in decent quantities for the past two years...
My chamber is officially 5.56mm (stamped 5.56 NM on the barrel), but I doubt it would be the problem : my jams are very symptomatic of a short-stroking bolt (due to the added friction because of all the crap on the bolt / carrier)
As a matter of fact, I did chrono XM193 ammo from PMC to build my drop chart : 3330 fps is pretty hot
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Your gun problem is partially (if not fully) ammo related.
If you are loading a 75 grain bullet with h4895 to 2900 fps your ammo is too hot.
3300fps out of that same barrel with PMC, my guess is the chamber is tight (read maybe not even cut to a Wilde profile) and needs a lighter load with slower powder to operate.
You could try a carrier weight or heavier buffer to see if it has any effect in the interim or to diagnose it, but that isn't or shouldn't be a long term solution.

It would be interesting to know what gas block that Armalite has as well. If it is the stainless clamp-on type, they are a pos.
I would change it out to a fully enclosed one, glued and screwed to the barrel.

Ar180shooter said:
Just a note on twist rates and AR's, but a 1/7 twist is completely unnecessary in a rifle that isn't shooting the U.S. Issue super long tracers. A 1/8 will stabilize up to 80gr VLD's, which are about as long as you can seat in a round feeding from an AR magazine.
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'Completely unnecessary' is complete bullsh!t.
What 80 gr. VLD bullets are you loading to mag length?
 
cr5 said:
Like I said, the piston AR solves a problem that wasn't there in the first place. We agree on that point.
The DI system is a great system and is a piston rifle, an internal piston system, I understand exactly how it works, which is why I own both types of AR's.
Even Eugene himself must have seen advantages in the external piston design though, why else would he have designed the AR-18 as a replacement for the AR-15? It probably would have taken off but the US military had already spent too much money on the AR-15 platform to consider switching over.
It's nice to have options though and the external piston system does have a couple advantages. Weight and increased part count are not advantages of the external piston operated rifle but it isn't enough of a drawback to care about as a civilian recreational shooter. I don't shoot enough in a day to actually worry about one running cleaner than the other and as for heat build up the DI rifle BCG and upper receiver get a little warmer but on a piston rifle the forend seems to get warmer.
I couldn't care less about Kevin's take on suppressed rifles. I'm not allowed to own a suppressor and I've only ever shot 1 rifle with a suppressor so it doesn't apply to me in the least. Doesn't apply to 90% of Canadian shooters so who really cares?
As for accuracy, well the DI system has more potential but if comparing two high end AR's the difference is slight. My 12 inch PWS can shoot sub moa and as far as I'm concerned that is more than good enough for anything an AR will be used for.
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Generally agree with the DI vs piston view here. That being said PWS does make some nice stuff as does LMT etc. I will add that the accuracy results are often applesto oranges. Yes you can get sub moa from a piston AR. Heck my Swiss Arms PE90 shot just under Moa at 100. But... Many of these piston systems are using very good barrels. Core and PWS come to mind with their SS barrels on their piston AR rifles. HK also uses a heavier match like barrel. By doing this they can match the accuracy of a DI rifle with a very good chrome lined hammer forged etc barrel. Put that high end barrel on a DI rifle and you're looking at 1/2 to 3/4 moa results rather than going for sub 1 moa.

The piston design that really interested me was the ADCOR. It's a hybrid system. There's a DI like tube off the barrel which goes to the piston system. The piston system is actually in the free float handguard. So no barrel harmonic issues as it's not connected to the barrel. Plus an auto dust shield/scraper on the bolt to close off the port opening when the bolt is closed. Last a non reciprocating charging handle like the FN FAL which is great in prone or with large optics. Adjustable gas block as well.

The ADCOR completed two rounds of independent testing with 6000 rounds each. No failures which was something of note as that wasn't known to happen with AR rifles. Accuracy was sub moa using heavy match ammo. The barrel? ER shaw barrel, chrome lined. Not a SS match type barrel. Just a very high quality regular barrel. The current ones have the option of a FN 249 barrel. Sub moa DI accuracy, piston reliability with hard wear non match barrels.

Like I said this is the only piston AR I own. The rest including all of my AR308 rifles are DI.
 
charlesquik said:
We dont have suppressor problem solved and the fact alone gas isnt coming to my face and that I dont have to clean often the gas tube was a huge factor for me. When im shooting the DI ar15 of my father I hate the gas on my face and it smell toxic. About the more weight and the more parts, I dont care because I bought a quality AR15 from pws and it is lightweight and reliable
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J'ai encore jamais lavé un tube à gaz. D'ailleurs, je suis gauché et même à automatique j'ai pas de problème avec du blowback dans ma figure. Étrange.

Cr5: AR's rock, no doubt about it. Kevin was actually talking about how pressurization of the DI bolt compares with the piston system bolt in terms of dealing with blowback.
 
beltfed said:
'Completely unnecessary' is complete bullsh!t.
What 80 gr. VLD bullets are you loading to mag length?
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What exactly are you saying here? Are you saying that a 1/7 twist is actually needed for a civvy shooting service rifle? If so, when is it needed? You seem to think that a 1/8 will stabilize a heavier bullet than one would typically load to mag length (with which I agree), so where does the disagreement come from? My whole point was that a 1/7 is not optimal as a 1/8 will do everything for you a 1/7 will do. This doesn't mean you shouldn't get a 1/7, just that the twist rate of 1/7 vs 1/8 should take a back seat to other features that are important.
 
jackrabbit000 said:
x2...the bullet is long gone before the action cycles. And the guy pulling the trigger has a lot to do with the accuracy.
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The thing that makes piston guns less accurate is the residual vibrations of the barrel. The DI version has inline movement which has less of an efect on the barrel. The piston guns on the other hand have a slightly above bore movement from the piston which makes the barrel vibrate which throws off your next shot. Thats why shorter and heavier barrels are more accurate.
 
Caleb314 said:
The thing that makes piston guns less accurate is the residual vibrations of the barrel. The DI version has inline movement which has less of an efect on the barrel. The piston guns on the other hand have a slightly above bore movement from the piston which makes the barrel vibrate which throws off your next shot. Thats why shorter and heavier barrels are more accurate.
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Under rapid fire situations, I don't think the shooter is really concerned about accuracy. Shooting from a bench is a different story, you're usually not shooting that fast between shots. Residual vibration would probably be nonexistent at this point. Just sayin'.
 
Interresting to learn that the barrel is the strong link here and the system would be less important... JP.
 
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