Piston AR, best accuracy?

I am just going to point out that DI ARs are very reliable and mine often go weeks without maintenance at competitions just to prove the point.

This is very true.
Your DI rifle shouldn't have problems after only a couple hundred rounds. Should only need a little oil every few hundred rounds. My DI rifles have never given me problems that a drop or two of oil couldn't solve.
 
I think you should just try different ammo/powder and check for problems with your gas system before switching to a piston system.
An AR shouldn't gum up like that after only a day of shooting.

I have to agree with you, it definitely shouldnt be gummed / dirty like this after 200 rounds fired, but still, this rifle, freshly cleaned and lubricated (I'm using Militec), is filthy by the end of the day.

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.

OP, what powder are you using? I know one shooter having problems with AR Comp. Is that what you happen to be using?

Also, what us you barrel chambered in? Had my 223 reamed to 223 Wilde, never had a problem after that (was a jam-o-matic before reaming)

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)

Sounds like your problem is the gun, not the fact that it is DI. Is it time to change worn out parts? How many rounds has it shot?

This rifle has about 5-6k rounds down the tube. I've replaced gas rings last fall, but aside from that it's all original.
 
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You can also get PWS from iRunGuns, just go to the US site irunguns.us and follow the directions.
I have had good luck with both site sponsors but it is good to have some choice as well, should you need it.

Anyway I have had several PWS rifles and continue to do so based on the accuracy even given the piston design as well as the reliability.
DI guns work great and I have them as well but when it comes to piston if you have your mind set on getting one, PWS makes one of the finest. I have had LMT, LWRC, Adams and other and I would trade them all (and have done so) for a PWS rifle.
Also as a note should you need to talk to support at PWS they are fantastic with good hints on all kinds of information, to loads and bullet choice to just questions about the rifle in general, a very good company that stands behind there product.
 
I have to agree with you, it definitely shouldnt be gummed / dirty like this after 200 rounds fired, but still, this rifle, freshly cleaned and lubricated (I'm using Militec), is filthy by the end of the day.

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.

I use H335. It is recommended for AR's.

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)

Weak load / dirty brass & chamber might be the culprits. What is the condition of the cases? Does the rifle short-stroke with factory ammunition? I recommend you buy some hot factory 556 loads and try them out. What do the casings look like after being shot? Do they go from shiny to scratched-up on the exterior after firing? Your chamber could be rough/dirty and causing excessive friction on the brass during extraction and robbing them of the momentum needed for ejection.

This rifle has about 5-6k rounds down the tube. I've replaced gas rings last fall, but aside from that it's all original.

Won't hurt to perform function tests on the extractor/ejector springs and gas rings.

The last thing you should do to fix this is dump 3K on a piston AR for all their so-called merits.
 
I use H335. It is recommended for AR's.

Can't agree more, sadly, it's hard to find these days, but on the other hand I've managed to score a 40 pounds lot of 4895.

Weak load / dirty brass & chamber might be the culprits.

My load is rather on the hot side (running 75 grains at close to 2900 FPS)

Also, my personal pride it to have reloaded ammo that's looks newer and shinier than factory, so I doubt it'd be the culprit.

What is the condition of the cases?

Once fired IVI, fully resized and trimmed to 223 dimensions.

Does the rifle short-stroke with factory ammunition? I recommend you buy some hot factory 556 loads and try them out.

At the end of the day, the rifle seems to short-stroke with anything I feed it. During the same day, I shoot shoot short-range targets with PMC XM193 55 grains, which are loaded to 5.56mm specs (read HOT!) and they barely cycle the bolt properly (misfeeds, partial feeds, bolt side-scraping the next round)

What do the casings look like after being shot? Do they go from shiny to scratched-up on the exterior after firing? Your chamber could be rough/dirty and causing excessive friction on the brass during extraction and robbing them of the momentum needed for ejection.

They seem to be the usual 'dirty' and 'scratched'. Slightly blackened at the neck. No excessive scratching, some 'dinging' due to the shell deflector.

I usually clean the rifle troughoutly on the eve of each match, it works flawlessly until maybe the last quarter of the day.
 
Until you put the PMC over a crono it is only advertised as being loaded to M193 specs.
What do you lube with? and throw some new gas rings in it.

As for Wylde chambers reducing reliability? BS on that one.
 
Until you put the PMC over a crono it is only advertised as being loaded to M193 specs.
What do you lube with? and throw some new gas rings in it..

Yes, this also. Apply some FireClean to the bolt lugs, the bolt, gas rings, the 4 rails on the bolt carrier that ride inside the upper receiver, and in the chamber.
 
Do you maybe have a cracked gas tube inside the upper that is letting more gasses into the upper but still getting enough into the BCG to cycle when it's clean?
Maybe the gas key is slightly loose? I had an Armalite rifle last year that the BCG gas key come loose and it took a while to figure out why it was cycling erratically. It would cycle for a few then short stroke then go a couple more.
 
Until you put the PMC over a crono it is only advertised as being loaded to M193 specs.
What do you lube with? and throw some new gas rings in it.

As a matter of fact, I did chrono XM193 ammo from PMC to build my drop chart : 3330 fps is pretty hot

Yes, this also. Apply some FireClean to the bolt lugs, the bolt, gas rings, the 4 rails on the bolt carrier that ride inside the upper receiver, and in the chamber.

Well, I'm doing pretty much the same with Militec instead, minus the gas rings. Was taught in the CF to never oil these.

Skip lubing the chamber and all the other spots should be wet with lube.

Barrel & and chamber aren't getting any oil

Do you maybe have a cracked gas tube inside the upper that is letting more gasses into the upper but still getting enough into the BCG to cycle when it's clean?
Maybe the gas key is slightly loose? I had an Armalite rifle last year that the BCG gas key come loose and it took a while to figure out why it was cycling erratically. It would cycle for a few then short stroke then go a couple more.

Didn't think of that, I'll disassemble it and take a look at the gas tube to check it's integrity, hard to see under the FF rail. Will check the tension on the gas key screw as well. Thanks.
 
Didn't think of that, I'll disassemble it and take a look at the gas tube to check it's integrity, hard to see under the FF rail. Will check the tension on the gas key screw as well. Thanks.

If it's the tube it's probably cracked inside the upper where the gas key slips over it. Would explain the excessive fouling in the breach and chamber
 
Sounds like your current rifle can be easily fixed and will no doubt give good accuracy with the right ammo.

For piston AR rifles, lots of good options mentioned. Also check out ADCOR piston rifles. The only AR piston rifles I own, the rest are DI.
 
Sounds like your current rifle can be easily fixed and will no doubt give good accuracy with the right ammo.

For piston AR rifles, lots of good options mentioned. Also check out ADCOR piston rifles. The only AR piston rifles I own, the rest are DI.

Yes, forgot about ADCOR, they have an awesome piston system, kind of a hybrid system that gives as close to a true free float barrel as is possible on a gas gun. I would go with either PWS or ADCOR. HK is nice but double the money and I don't know if they are twice as good to justify the price.
I'm sure you'll figure out the problem with your DI rifle soon and then spend $50 or less to fix it and realize you don't "need" a piston rifle.
Biggest problem I see with piston rifles is that they are all proprietary gas systems, you can't just go into the local gun shop and find parts unless they are a distributor for that brand of rifle. With a DI rifle everyone carries parts because they are all the same.
 
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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