Piston Driven AR-15s

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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?
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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?
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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?
 
What model do you use? What do you use for lubrication and how do you apply it?
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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.
 
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.
 
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.
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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.
 
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?
 
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.
 
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.
 
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.
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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.
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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.
 
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.
 
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.)
 
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.
 
Perpetual newbie question on this topic

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
 
am I crazy.....or was it not Daewoo (NOT HK or SIG) that actually developed the first AR piston system? Remember the DR-200?
 
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