Piston Driven AR-15s


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Soldier0117
April 9, 2008, 05:06 PM
Who do you think has created the best piston driven AR-15 style rifle. Heckler and Koch with the HK 416, LWRC with the M-6, or Barrett with the REC-7 (6.8 mm.)?

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Deer Hunter
April 9, 2008, 05:08 PM
How about Stoner with the AR-180?

:)

R127
April 9, 2008, 05:51 PM
This seems like a good thread to ask the following question, why do you want an AR-15 with a piston driven gas system?

Bartholomew Roberts
April 9, 2008, 07:02 PM
An interesting question would be "Who here has shot all three piston rifles that you mentioned?"

LegalAlien
April 9, 2008, 07:18 PM
An interesting question would be "Who here has shot all three piston rifles that you mentioned?"


mmmmmmmmm . . . slightly more than 3 . . . . add the SIG556 to start with, then add the new releases not available yet, such as the FN SCAR, or the Bushmaster ACR aka Magpul Masada

Looks like a new trend in AR design does it not? Wonder why?

Is it maybe because the FN FAL gas piston design has been so succesful for so many years? Just wondering. . . . . .

lee n. field
April 9, 2008, 09:02 PM
I thought this thread was titled "PURPOSE-DRIVEN AR15", and immediately assumed you were talking about rifles being used in modern church services LOL

I know of what you speak. Euuuu.

Soldier0117
April 9, 2008, 11:46 PM
The reason I want a piston driven model is because I have no care for the dirty and unreliable direct impingement system. Has anyone at least heard which of this are good? Lastly if no one has shot any ARs that come with the system as a standard, has anyone tried a piston conversion such as the one by Osprey?

TestPilot
April 10, 2008, 08:43 AM
This seems like a good thread to ask the following question, why do you want an AR-15 with a piston driven gas system?
Because I don't like rifles that will run reliably only under a running shower of CLP?

An interesting question would be "Who here has shot all three piston rifles that you mentioned?"
I don't think it really matters. People who looks for piston driven AR15 does it because of reliability factor. And, reliability of a certain rifle model is one factor that cannot be jusdged by one individual picking up a one specimen and shooting it. Best way is to collect as many user review as possible, and get a statistic.

For example, I have a SIG that I am very satisfied with. But, if I made the purchase decision based on few range rental SIG I fired before I bought mine, I would have never bought a SIG, because few of those SIG rentals malfunctioned. I still bought my SIG because of the statistics indicated it was reliable, inspite of my range experience.

Besides reliability, I have no reason to think why a piston AR15 would shoot and operate any different than a regular AR15.

everallm
April 10, 2008, 08:46 AM
Add to the list of purpose built piston AR format the Robinson Arms XCR.

Bartholomew Roberts
April 10, 2008, 10:43 AM
Well since we seem to be sold on the concept that DI cannot possibly be reliable and that it isn't necessary to actually handle a weapon before commenting on which one would be the most reliable rifle, I will bow out of this conversation.

R127
April 10, 2008, 02:06 PM
So it is the reliability thing. That's something I could never figure out about AR's. Some people swear the last AR that had reliability problems was built in the 60's and then you have other people engineering gas piston systems. I'm not saying I disagree with the gas piston AR's, it's pretty well established at this point that no matter how good your direct gas impingement system is it will never be as robust as a piston driven system.

I don't have any experience with piston driven AR's so I can't make any specific reccomendations. I will say there's a whole field of rifles specifically designed around piston driven systems and one of them might be a more cost effective solution.

Assuming small arms development isn't completely hamstrung by another AWB it will be interesting to watch the progression of AR's transitioning to piston driven gas systems and AK's being built for match grade accuracy.

Tom Servo
April 10, 2008, 02:24 PM
Well since we seem to be sold on the concept that DI cannot possibly be reliable and that it isn't necessary to actually handle a weapon before commenting on which one would be the most reliable rifle, I will bow out of this conversation.
Awww...c'mon! It's the internet! :)

Because I don't like rifles that will run reliably only under a running shower of CLP?
Perhaps we could have some clarification on this? Mine runs fine with only cursory cleaning, as do most AR's I've seen. If you want to pack your rifle with mud, run it over with a truck and run it through a rock tumbler, be my guest. I tend to be a bit nicer to things I invest large amounts of money in.

I've fired the XCR, the Sig 550 and a piston-driven Bushmaster. All three were good shooters, and I encountered no problems. It should be noted that all three are vastly more expensive.

The only thing I noticed was that firing .223 through a piston-driven system feels weird. Recoil is slightly reduced, but I can't see spending a few hundred dollars extra to rectify what is a largely non-existent problem these days.

RedLion
April 10, 2008, 03:07 PM
The fact that the companies building the gas piston ARs are interested in profit should be taken into account as well.

I don't believe it's much different than the high horsepower SUVs today. I don't think GM and Ford and others built those vehicles because they were needed, I think it was more because they saw an opportunity for cash.

Are either 'better'? It depends how you look at it.

briansmithwins
April 10, 2008, 05:59 PM
Where to start?

Retrofitting a gas piston onto a AR just doesn't make much sense to me: The original works fine and the 'fix' doesn't change the things that are the REAL problem.

When was the last time you saw an AR go down because of gas residue in the bolt carrier? Sand and grit, yes, smokeless powder residue, not so much.

ARs fail to function because foreign debris gets into the works. The minimal clearances and compact design of the upper don't allow the garbage anywhere to go. A gas piston will not help with this problem.

Gas piston retrofits also have problems:

1) Proprietary parts from manufacturers that may or may not be around when it breaks. Anybody still running a Rhino conversion? Got extra op rods?

2) Not proven. I want my SHTF firearms to have been manufactured by the millions. I want Garand ser# 4500000, not 0000004. Bugs get worked out in serial production. Proprietary gas piston systems manufactured in the 1000s (if that many) may never get past the buggy stage.

3) Adverse effect on reliability: Every gas piston system I've seen is using more parts than the system it replaces, a stainless steel tube. Many of these parts are small, of questionable robustness, and have unknown lifetimes. The AR already has too many small parts to get lost and if you've ever dropped a firing pin retaining pin you know what I mean.

The only positive I've seen from retrofitting a gas piston that is that lube may last longer than with DI. OTOH, a properly lubed AR will fire a basic load of 7 mags without needing additional lube. If you're burning more than that without a chance to clean (or at least relube) you should have brought something beltfed, or preferably fire support.

BSW

alpha6164
April 10, 2008, 07:20 PM
I have a POF (Patriot Ordnance Factory) HK416 rifle and its awesome. I have shot over a 1000 rounds without a malfunction. Last week i took the gun apart to see and it looks like it has never been shot. If you check out the reviews they have had by several magazines including Small Arms, etc etc some have shot their weapons upwards of 20,000 rounds without a single cleaning in full auto without a malfunction. I also just purchased an FN FS2000 which is piston driven and love it. I will never buy a DI system.

Any guns i buy have to be 100% reliable for doomsday:)

lonegunman
April 10, 2008, 07:53 PM
I bought a Sig 556 for my gas pistol experience. The system is tried and true from their 550 series and workmanship is top notch.

The only exception is the handguards, they were assembled before the rail installed and are a PITA to remove because of that. Everything else about the gun is first rate.

It has nearly 1000 rds thru it with no problems and no jams.

TestPilot
April 11, 2008, 03:25 AM
Well since we seem to be sold on the concept that DI cannot possibly be reliable and that it isn't necessary to actually handle a weapon before commenting on which one would be the most reliable rifle, I will bow out of this conversation.
This is one part where common wisdom fails. It's true. You cannot determine a reliability of a certain model by one person firing a single specimen, with a few exception. Most reliable method is to gather statistics from multiple users.
If anyone finds a logical of factual flaw in this, please tell me what it is.

Perhaps we could have some clarification on this? Mine runs fine with only cursory cleaning, as do most AR's I've seen. If you want to pack your rifle with mud, run it over with a truck and run it through a rock tumbler, be my guest. I tend to be a bit nicer to things I invest large amounts of money in.
I handled M4 while in the military. It cannot have malfunctioned because of improper cleaning, because we clean it until whoever inspects it will find nothing on the Q-tip when they swipe any part with it. Then we lubed it.

If the CLP we used in the army was not applied to a degree where it was dripping fron the gun, carbon build up would seize the bolt to a degree where I have to slam the butt of the rifle on the ground to get the chamber open after shooing close to a combat load, about 7 magazine, or sometimes not even that. The range session started with the gun squeeky clean, so if some contaminant on the bolt seize up the action, it cannot be from anything other than the DI action spraying contaminants inside the receiver. And they say the "crap where it eats" design is no problem.:rolleyes:

The only way to pervent that was to spray the inner with CLP in interval, to get a "running shower" effect. So that it will continuously flush carbon from building up. Seized up action? A very liberal spray of CLP to the forced open action usually fixed it. After that, if no CLP sprayed again after multiple mags, guess what happens? Seized up again. That's why range sergeants stand by at the entrance to the firing lanes with a big spray bottle of CLP in their hands. And, even then I can't rememebr a single range sesstion without at least one soldier having trouble with his M4 during years of army life.

No help from a truck or mud packing was needed to seize up the amy issued M4s. Situations where I need it may not be where I can be nicer to things. So, although I do pamper my personally owned weapons, I do not recommend ones that require me to pamper it.

Don't Tread On Me
April 11, 2008, 05:20 AM
Where to start?

Retrofitting a gas piston onto a AR just doesn't make much sense to me: The original works fine and the 'fix' doesn't change the things that are the REAL problem.

When was the last time you saw an AR go down because of gas residue in the bolt carrier? Sand and grit, yes, smokeless powder residue, not so much.

ARs fail to function because foreign debris gets into the works. The minimal clearances and compact design of the upper don't allow the garbage anywhere to go. A gas piston will not help with this problem.

Gas piston retrofits also have problems:

1) Proprietary parts from manufacturers that may or may not be around when it breaks. Anybody still running a Rhino conversion? Got extra op rods?

2) Not proven. I want my SHTF firearms to have been manufactured by the millions. I want Garand ser# 4500000, not 0000004. Bugs get worked out in serial production. Proprietary gas piston systems manufactured in the 1000s (if that many) may never get past the buggy stage.

3) Adverse effect on reliability: Every gas piston system I've seen is using more parts than the system it replaces, a stainless steel tube. Many of these parts are small, of questionable robustness, and have unknown lifetimes. The AR already has too many small parts to get lost and if you've ever dropped a firing pin retaining pin you know what I mean.

The only positive I've seen from retrofitting a gas piston that is that lube may last longer than with DI. OTOH, a properly lubed AR will fire a basic load of 7 mags without needing additional lube. If you're burning more than that without a chance to clean (or at least relube) you should have brought something beltfed, or preferably fire support.

BSW


Couldn't have said it better myself. I'd like to expand a bit if I can.

When you buy a system that is not military-approved and standard issue "in the millions" you are buying an unknown. The people who make that piston, what kind of steel is it? How long will it last?

Unknowns. Only known by the manufacturer, if they've conducted multiple 20,000rd tests to determine various factors such as wear, effect on reliability, rate of breakage ..and do so in a statistically meaniingful way.


Look, I HATE the AR-15's gas impingement FILTH. Nasty. Also blows out and dried out the lube so fast. However, with that platform I have an awful lot of knowns. It is known from extensive military testing that a carine length gas system's bolt has a lifespan of about 6,000rds.

The latest and greatest rifle out there that is hot off the assembly line, and has no military approval and is not being fielded anywhere - do you know how long that bolt will last? Maybe it will only last 2,000rds because they are using inferior metals. Or maybe it has a design flaw that wasn't detected in the early stages of development because so few rifles exist and so few independent or military tests were done.


Whole point is, when you go with something new or unknown, you are giving up a massive, almost complete wealth of knowledge on another system

AK-47 - proven.
AR-15 proven, same with FAL and others.

People even know the differences between original military parts quality and that from the aftermarket in terms of life-span and reliability for all three above platforms.


That has a tremendous value.


So when you take the plunge and buy that new rifle system - you are essentially becoming a "beta tester" ...

If you visit the SIG 556 forums and read around, you'll see that already there's been changes done to the handgards, to the magazine catch and elsewhere because the first batch of rifles showed problems.


I'm not going to bet my life on something that isn't tried and tested. 1911 platform. That's another one. If you buy a real one (no MIM parts) with quality parts, made well ...it is one super reliable, nearly unstoppable pistol. Junk MIM parts, poor fitting, over-accurizing/tightening of the action as well as the #1 culprit - crap magazines makes a lot of 1911's jam and finicky with ammo. But, with that platform, there's not going to be any new surprises or unresolved problems. Everything that can be imagined has been done and experienced with that platform. You're not going to run into anything that hasn't been seen or dealt with before.


I've been looking at the SIG 556. I might want to try out a piston system. Being a lot cleaner is appealing. Although, the cleaning you save in the action is often offset by having to clean the gas/piston tube. Still, it is cleaner overall. AK style bolt....

Speaking of which. AR-15 unreliability in the desert is primarily HK propaganda to push for their piston uppers.

HK does have a point. Yes, less carbon filth in the action is better. Also, a cool running bolt and carrier will not be subject to heat-stress and fatigue. Heat something to where you can't touch it, while exerting lots of force and you are wearing it down. So it is reasonable to see that a piston upper AR will increase the lifespan of the bolt - which is a weak part of the AR. But it does NOTHING to solve the issue of dirt and dust.

That's the HK's bait and switch. The problem is not related to their solution. The problem of sand/dust is the military's top concern when going to another platform. The military isn't as concerned about the other issues. After all, the U.S. military - after the adoption of the M16, kept on with its testing and trials and did experiment with a piston driven M16. Colt discusses this. They provided prototypes and the military tried them and saw no significant improvement.


Why? Because the problem lies in the bolt. It has tiny lugs and the fit to the carrier as well as the carrier to the upper doesn't allow grit, sand and dust to get out of the way. Compare that to the AK which is very loose by design. AK has less lugs, more carrier mass with a long stroke slamming down on the round, it has tapered ammunition, a fixed ejector, an overpowered extractor...so forth an so on. There's more, but that's the gist of it.


Piston AR's offer no solution whatsoever to the sand/grit problem.

That being said, in a clean environment - a gas impingement AR can run well over 240 rounds (8 full 30rd magazines) without a single failure and without a cleaning or a lube. That is a full load-out. In many cases, thousands of users have done twice that without failure, and others 3-4x that amount only adding some lube. That shows the carbon fouling is not a problem.

Remember, the M16 wasn't designed to be used be mindless idiots who don't clean their rifles. Even the Red Army trained their men to clean their AK-47's after each use. Why? Because it is common sense and a good precaution regardless of the inherent reliability of the platform. You know, they do make stuck-case removers for 7.62x39mm for a reason. Abuse can lead to problems in anything.



For me, it's the AK or the AR. The new guns hitting the market now will be a lot of fun for action-shooting and as a range toy. It's going to be some time before the various trials are done and finished and many reports come in. Even if they are approved and fielded, reports still show weaknesses, suggested schedule of maintenance etc....all useful.


Just look at the PDF's Barth has posted in the past. That is just a sample of the documents available for the M16 system. There are thousands of pages written for hundreds of tests, done by the military with thousands of rounds of ammo fired. I don't think there's a rifle or system out there with such a massive amount of analysis and testing done. It is the most documented rifle on Earth.

TestPilot
April 11, 2008, 07:15 AM
Whole point is, when you go with something new or unknown, you are giving up a massive, almost complete wealth of knowledge on another system

AK-47 - proven.
AR-15 proven, same with FAL and others.
AR -15 Proven? Of course it is. Proven to still jam after decades of adoption and changes. I'm supposed to be comforted by this?

Speaking of which. AR-15 unreliability in the desert is primarily HK propaganda to push for their piston uppers.
It was plenty unreliable in the in the military range without being in the desert.

Piston AR's offer no solution whatsoever to the sand/grit problem.
This is not the only problem. 100% for the failures I've observed related to M4 was not foreign sand/grit. The top cause was carbon the DI system sprayed on the inner seizing up the action, followed by poor magazine.

Just look at the PDF's Barth has posted in the past. That is just a sample of the documents available for the M16 system. There are thousands of pages written for hundreds of tests, done by the military with thousands of rounds of ammo fired. I don't think there's a rifle or system out there with such a massive amount of analysis and testing done. It is the most documented rifle on Earth.
If I have an M4 with a seized up bolt carrier in my hand, and I don't have a massive spray bottole of CLP with me, that thousands of pages of written documents will help me how?

I was one of the people who said, "DI AR15 is okay. They are dirtier, but with proper maintenance it will run reliably." It was because that's what army is saying in the press, and they still try releasing some surveys about soldiers being satisfied with M4s, they never came around to ask me though. AR 15 system being reliable was what I wanted to believe about the rifle U.S. army was using, and for the complaints, I assumed most of them were comming from people who did not knew better.

That was my attitude until I actually had to deal with it in the military and be the one who has to wonder if that thing would seize up before I even finigh up shooting combat load.

BsChoy
April 11, 2008, 08:03 AM
In my experience with the original DI system AR's and having fired thousands of rounds and watched thousands more be fired I cannot remember seeing one carbon build up related malf? This is with base model Bushmaster patrol rifles in M4 and A3 config's.

I have to say pistol driven really intrigues me but like I said its not an overly troublesome system in my opinion.

jason10mm
April 11, 2008, 09:25 AM
I wonder if the piston systems will take over in the next 10-15 years, especially if the military moves away from the M16-based systems.

I think the AR-15 platform is here to stay for a long time in civilian hands (barring legal action) due to its modularity and ergonomics, but if piston uppers can be made for the same price and involve less cleaning and gain an air of "improved reliability" then I could see them becoming more popular, especially if the Cerebus owned lines add them to their catalogue.

Don't Tread On Me
April 11, 2008, 05:40 PM
I reference the military reports, but I always rely on my personal experience. I have yet to have a single failure in my AR-15's and I don't exactly clean them often.

That's a lie, I had one failure. I had a stuck case (Wolf ammo) and that was after firing in excess of 500 rounds of that filthy crap without a single cleaning whatsoever.

Regular ammo - never a single malfunction. I use USGI mags and I have good AR's.


If carbon fouling stops them, I don't know how much more dirty to get them so that they jam as a result of it. I've had good reliability run wet or even after they dried out from so much shooting. The gases heat the oil and burn it off, they blast the oils out and the carbon soaks it up and dried up the action. Despite that, it still runs.


Now, aside from my personal tests - when I am regularly maintaining my rifles, I've NEVER ever abide by the whole "run em dry" philosophy that seems to have started from Gulf War I. I've always lubed them and lubed them generously. Nice and wet. Now, like I said ...I've run them after they were crusty and dried out with full filth and they kept going, but its always better as a precaution to keep them lubed.


To me, those parts are a tight fit, a lot of friction areas, subject to heat and dirt and the gas rings/carrier reminds me of piston in a cylinder of a motor. Do you run a car engine dry? Nonsense. I've always lubed them and they run great. Even during my filth tests they ran when dried out from lack of maintenance.


I view the AR's system as having flaws ---- but my whole point is that the flaws are known, the lifespan of the parts, system and schedule of maintenance, parts etc are all KNOWN quantities. The AR's system is simpler. Less parts with just a gas tube. But, you pay for that with more heat/filth. Yet, that really isn't a problem either because carbon does not make the rifle unreliable...especially if you clean the rifle after 240rds which is a full load out. Keep in mind, that the vast majority of AR opinions out there are based on junk AR's made of non-spec parts and metals and lack testing processes. A lot of the opinions are based on the testimony of people whose cleaning and oiling habits vary from excellent to worse than a conscript who's never held a gun before.


Whatever the case, due to the AR's system and it 40+ year military service and adoption in dozens of nation, service in multiple wars, and hundreds of tests and massive widespread civilian use in competition from highpower to 3-gun ...there's a lot of data. So much so, I know what to expect and when to expect it. I know what to do and what not to do.


I can work around that. I can't work around the surprises produced by what are minimally tested prototypes or new-concept firearms.

cracked butt
April 11, 2008, 05:54 PM
Piston ARs make some sense if you don't like cleaning rifles very much (still have to clean the gas tube and piston which would seem to me that there would be some loss in accuracy after a cleaning as the mechanical pices 'settle back in' after reassembly). They are an answer to a problem that doesn't exist when it comes to reliability.

JHansenAK47
April 11, 2008, 07:30 PM
Is it maybe because the FN FAL gas piston design has been so succesful for so many years? Just wondering. . . . . .

The gas piston works. However they still had to add sand cuts because they would jam in dust. Go google the problems the Israelis had with their FALs jamming.
Why? Because the problem lies in the bolt. It has tiny lugs and the fit to the carrier as well as the carrier to the upper doesn't allow grit, sand and dust to get out of the way.
Very similar to the problem the FAL had. The bolt is binding in the receiver. Piston ARs and DI Ars use the same bolt. Military bolts are usually parked. Remember the parked M9 mags having issues. They didn't redesign the mag they just redid the finish. Point being it is not just the gas system causing failures.

Bartholomew Roberts
April 11, 2008, 08:22 PM
You cannot determine a reliability of a certain model by one person firing a single specimen, with a few exception. Most reliable method is to gather statistics from multiple users.

And how do you propose to gather statistics from multiple users if according to you it doesn't matter how many people here have even used the weapons in question? Where else are you going to get comparative statistics for the weapons mentioned by the original poster except from people who have used all three weapons?

As for your experience with the M4, all I can say is that I have never had the same problem either in the military or in owning/building/shooting these rifles the past 17 years. In fact, I commonly run my rifles 500-750 rounds without adding additional lube. I also use a suppressor which both increases heat and the amount of carbon blown back into the chamber.

How much of your military experience was livefire and how much was blanks?

theotherwaldo
April 11, 2008, 08:55 PM
Once you fellas figure out what works best, tell me and I'll buy one.

-Might as well sit back and get comfy.

I'm gonna be waiting a good, long while.

TestPilot
April 11, 2008, 09:15 PM
Originally Posted by Test Pilot
You cannot determine a reliability of a certain model by one person firing a single specimen, with a few exception. Most reliable method is to gather statistics from multiple users.

And how do you propose to gather statistics from multiple users if according to you it doesn't matter how many people here have even used the weapons in question? Where else are you going to get comparative statistics for the weapons mentioned by the original poster except from people who have used all three weapons?
I did not state it does not matter how many people used it. I stated I don't have to gather data by first hand for the purpose of judging reliability of a certain model.

As for your experience with the M4, all I can say is that I have never had the same problem either in the military or in owning/building/shooting these rifles the past 17 years. In fact, I commonly run my rifles 500-750 rounds without adding additional lube. I also use a suppressor which both increases heat and the amount of carbon blown back into the chamber.

How much of your military experience was livefire and how much was blanks?
My post was strictly based on live ammo. I don't care about blanks. I have no problem beliving you fired 500~750 rounds with your rifle without additional lube. It's just that I would not pick up a standard M4, clean it and lube it with a coat of CLP, and trust my life, nah not even betting a dollar, on it to do the same.

What model do you use? What do you use for lubrication and how do you apply it?

Bartholomew Roberts
April 12, 2008, 12:33 AM
What model do you use? What do you use for lubrication and how do you apply it?

Model wise, I've used M16A2s and multiple variants of the AR15 (11.5", 16", M4gerys, midlengths, etc.). The two that have consistently done 500-750 rounds without lube were my 16" Bushmaster HBAR and my 16" MSTN midlength.

As for lube, I used CLP on the Bushmaster and SLIP 2000 on the MSTN. Application is a drop down each rail of the bolt carrier, a drop on the gas rings, and a drop smeared over the body of the bolt.

Lobotomy Boy
April 12, 2008, 01:22 AM
The AR system is reliable enough for me to trust my life to it in the climate in which I shoot, hunt, and if the S hit the F, I would fight. I live in a climate of forests and lakes, not sand dunes and windstorms. I trust the system enough that I just ordered a DPMS LR308L and a RRA 6.8 upper for my M4. That said, it does look like the battle rifle of the future will use a gas piston to cycle a round with a larger caliber bullet. My money is on a piston conversion upper for existing lowers that shoots the 6.8 round. That would be the most logistically feasable and affordable change for the military to make.

TestPilot
April 12, 2008, 07:48 AM
As for lube, I used CLP on the Bushmaster and SLIP 2000 on the MSTN. Application is a drop down each rail of the bolt carrier, a drop on the gas rings, and a drop smeared over the body of the bolt.
If there's one thing I can agree with you is that that is what a rifle SHOULD need for lubrication. Problem I had was that was not what the M4s I had DID need for lubrication. When I got to my first duty station, I did that exact same thing. I tried it on about 3 different M4s. I had to stop doing it after my rifle seized up after shooting about 4~5 magazines, and getting a dirty look from my sergeant who banged my rifle to force the bolt open for me. The inside of the receiver saturated with CLP melted the carbon and the rifle starts working again, with the CLP dripping through all openings. I hated the drip and all the dirt it attracted, but that was the only way it worked. That was with CLP. I can't comment on SLIP 2000, since I have no knowledge about it.

stubbicatt
April 12, 2008, 07:52 AM
There is merit to directing the inquiry to the cause of the problem, which as I understand it is really 2 causes: 1) The DI gas system, and 2) the very tight bolt carrier-to-receiver clearance not allowing room for smuts and dirt.

By this analysis, the gas piston fixes #1, but does nothing for #2.

Perhaps an entirely different design is in order.

I have not seen one, or held one, but the Bushmaster ACR due out any day now seems to have at least #1 under control, and they suggest that #2 is also fixed due to the bolt carrier riding on steel rails in the receiver. Supposedly the Robinson Arms rifle also addresses this.

Anybody shot the Robinson and noticed any issues?

ctdair
April 12, 2008, 08:05 AM
I have never experienced a failure due to a dirty upper on a Ar-15 in Civilian Life nor on M-16 during 7 years in the US ARMY. It was easier to report all training ammo as expended than try to turn it back in , I have fired blanks which are the dirtiest thing you can fire in Your M-16 , we fired and fired and fired for several hours to expend all the blanks for a Battalion through 3 M-16's , the gas tubes actually turned red from the heat. No stoppages.

JoeLad
April 12, 2008, 08:08 AM
It's not fair comparing civilian owned AR15s to the military M16 series of rifles.
Not many AR15s will be fired nearly as much as a military rifle.

That siad, I own a gas piston AR. A LWRC conversion. It works extremely well.

TestPilot
April 12, 2008, 08:10 AM
There is merit to directing the inquiry to the cause of the problem, which as I understand it is really 2 causes: 1) The DI gas system, and 2) the very tight bolt carrier-to-receiver clearance not allowing room for smuts and dirt.

By this analysis, the gas piston fixes #1, but does nothing for #2.

I don't think the bolt carrier to receiver clearance is that tight. Yes, it is true that it is pretty tight in there in the upper receiver, but the part of the bolt carrier that is actually touching the inside wall of the receiver is the rails slightly protruding from the bolt carrier. The problem was more of an increased friction issue. The contact area is about the same. The rails from the bolt carrier, and the bolt contacting the locking surface of the end of the barrel. When it's just a metal surface with CLP, it will slide. But, as soon as it gets covered with carbon sprayed on by the DI system, the friction will spike up.

I can see how large foreign debris can cause a problem with tight space, but that was rare.

It's not fair comparing civilian owned AR15s to the military M16 series of rifles.
Not many AR15s will be fired nearly as much as a military rifle.
I don't have a problem with that. Some civilians, such as a few here, fires as much, if not more, than most military infantry soldiers do. And, rifles like AK47 and FAL often gets compared to, which are all military adopted. I don't accept double standard for military and civilian rifles as long as both are bought for combat/ self defense.

Lovesbeer99
April 12, 2008, 08:33 AM
Sorry if this was already covered, but I just got a new Bushmaster catolog that has a new gas piston AR, and also a gas piston conversion system.

rino451
April 12, 2008, 09:12 AM
While I like my FAL and like the AK in general...

Gas piston AR's = the latest fad to separate those with BRD from (more of) their money. (Retailers know that that plain jane AR that you have is fine once you know what you're doing with it and that it will last years and years if maintained properly.)

:uhoh:

That said, in shopping for an 7.62 autoloader, I have my eye on a SCAR-H vs. AR-10 variants, mainly to support what FN is doing in the US.

I'm also one of those guys who has wundergunz that can shoot more than 300 rounds between cleanings. I had one that I shot 3-4 weeks ago at a rifle class (irons out to 500) that I haven't cleaned in easily 2000 rounds and believe it or not, was shooting it dry. I popped the bolt and carrier for a couple of guys at a carbing match when I heard all this blather about drenching then in lube, and the bolt and carrier were bone dry. The range owner/friend cracked up and scolded me telling me I should know better. I told him that it shoots and that I didn't want to jinx it. (I listened to him and cleaned it a couple weeks later, though.)

Soldier0117
April 12, 2008, 12:36 PM
Has anyone heard about or tried the Adams Arms conversion? Check it out by googling ar15fix.

collateral
April 12, 2008, 02:38 PM
Piston driven ARs are cool and all, but I think I'll save my money and buy extra parts for my DI bushmaster. I'd like to have enough parts to rebuild anything on that rifle, as many times as I'd need to.

yhtomit
April 12, 2008, 02:40 PM
Hi! At the risk of excessive thread drift, I hope someone can enlighten me on this:

I know this may seem excessively obvious, but:

Is it fair to describe the difference between the two system (gas v. piston) as being about *where* the gas pressure has its effect? That is, my understanding is that in a piston-driven arrangment, the same gas which would travel the length of the gas tube to operate the bolt in a conventional gas arrangement travels instead a shorter distance, pushes a rod (piston) at what would be the beginning of the gas's travel path in the gas system, and this rod actually does cycles the bolt.

I'd really appreciate a link to a how-things-work style diagram, or an "exposed interior" shot comparing the two action types.

Cheers!

timothy

hilltopper55
April 12, 2008, 08:36 PM
Bill Ruger designed a gas piston Mini-14 223 after the M-14. He made the right choice first and skipped the DI action. I believe the Kel-Tec Su-16 is also a gas piston design. Just food for thought.

volfandan
April 13, 2008, 01:15 AM
am I crazy.....or was it not Daewoo (NOT HK or SIG) that actually developed the first AR piston system? Remember the DR-200?

kulak
April 13, 2008, 05:18 AM
I'd really appreciate a link to a how-things-work style diagram, or an "exposed interior" shot comparing the two action types.

Here is a link to a nice visual for the internal workings of each design..

http://www.armytimes.com/projects/flash/2007_02_20_carbine/

yhtomit
April 13, 2008, 08:28 AM
kulak:

Amazing! Those illustrations are precisely what I was looking for, and they matched my understanding as well (makes me smile). Thanks for the help.

timothy

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