It isn't firing dirt that stops the M15/M4s.  And no piston keeps foreign dirt out any better.

IMO the only advantage you get with a piston over a DI rifle is that you are not venting heat into the bcg. But if you think that by slapping a piston into an AR you now have an AK, you are kidding yourself.

I like the DI and the piston systems and have both. For the sake of an opinion though, if the piston system wasn't as good as or better than the DI then I don't think
Colt, or the rest of the major manufactures would be producing them more and more.

Good point. I would hope that the top manufacturers would not put out an inferior product just to satisfy customer demand.

That said. If you do not want a piston then do not buy one and let the market settle the dispute.

Just to throw something else out there.  I was talking to the sales people at the LMT booth at the last SAR show and was asking about there piston guns and how much of a difference it really makes.  I was told that it was not really necessary for the ar platform, but that is what people want right know, so they made it.

PS.  I don't have an opinion one way or the other.  I think both are good designs but consider the pistons guns over priced

Back in the 60s the same question was asked, Colt made piston M16s for the government to test.  What they found was that it didn't make a whole bunch of difference the piston guns and the non piston guns.  That in long run testing both systems had a comparable mean round between failure.  

Honestly 90 plus percent of failures are mag related, so if you don't change the magazine you have the same problems.

i
Ok I'll question yours, when they wear out "and they do" gas rings get thinner and can bend the band allows gas to blow buy and not power the syetem.

do you really think that the government and colt looked at both guns and said the DI is better because of this quality? it goes like this "the cheapest one to manufacture is the one that gets the deal" end of story

 

Piston rail systems are ugly to me. KAC RAS or NOTHING

DI works fine, no need for a change.

No I think that MRBF was so close that it didn't matter which system they went.  

Most malfs with the system are mag induced, changing the upper won't correct the problem.

Gas pistons are the new future? You do realize that pistons are not new to the AR, right? Have you ever heard of the AR-18 or AR-180?

And by the way, I can only carry 240 rounds in my chest rig. I guess I should buy a piston kit so I can blow through all of my ammo in 2 minutes, and then sit there like an idiot waiting to be shot. Yeah! Pistons are rad!

I've always approached this situation as the system was designed as a direct impingement...forcing a piston in there seems like a redesign to me.  I'd rather have a rifle deisgned from the ground-up to work with a piston than to retro-fit an AR15 to work with a piston.

My combat load is 13, 28 round mags I have been able to shoot that off in Iraq with my issue M4 without a problem.  That is dispite no more than 5 minutes of cleaning on my gun during the week and some heavy dust and dirt from the gun in the turret of the M1114.

I own some piston based guns and plan on getting some more piston weapons in the future, just to have them not because I believe they are inherently better than the DI system .

I read the same SAR article by Reed Knight but came away with a different conclusion.

His main complaint about piston uppers was carrier tilt. His context was using existing stockpiles of equipment and material not designing a piston upper from the ground up. He stated in the article that HK got the piston upper correct as the bolt carrier is designed differently than off the shelf AR bolts. The redesigned bolt helps eliminate the stress on the bolt.

Reed also confesses that he is not in the loop as he likes in listening to complaints about the M4 and M16 from troops using it Iraq and Afghanistan.

So, if you are not paying attention to the complaints about existing arms (as the M4 is well documented in having issues) from end users, how are you supposed to evolve?

Also, Reed states that he would not recommend building another 5.56 based replacement weapon for the M4/M16 as he is promoting a totally different caliber.

No kidding. It never ends.

I think aluminum is a poor choice of receiver material for piston rifles.

Moving the piston system out over the barrel (vs. inside upper), and having the piston hit a spot above the carrier as opposed to gas inside the carrier is going to cause more force flexing the barrel and BCG down, IMO.

I would expect that atleast a thicker aluminum upper, or a steel upper would be better to counter the wear described by the OP.

Testing has shown that an M4 can function with only 1 gas ring installed. Therefore, I detect a hole in your story.
Gas rings get worn around their circumference, not their thickness. Exactly which way did the ring in question bend?

Didn't feel like reading the other responses, but I will say...



DI FTW!!!



If you want a piston gun with good parts availability, get an AK

Is this the same for the Mcfarland{?} gas ring?

Focus here I am not the guy with the bent ring Nor am I the guy that called him out. I don't rely on studies that can't seem to be found. I fix dead guns and Have been an armorer for 15 years factory certified by Colt. Gas rings can loose tension and Bend in of you will allowing gas blow by. They also erode and become thinner any wear makes them "thinner " in a least oine dimension.  to say they can't be bent is ignorant because you nor I have seen everything that can happen I imagine with enough hot rounds and no cleanimng a ring could degrade enought to be bent free of  the channel.

In a word No. The McFarland is new and they work great, Colt does not endorse teh use, as the typical Gas ring test by sitting the bolt carrier on teh extended bolt to see if the tension keeps it standing does not work with Mc Farland rings. The Mc Farland is a one piece design that is twisted in the channel wher eteh three rings normally ride. The Macfarland is designed to provide a better more uniform seal. My personal experience is taht they last 50-60% longer that regular rings in our SBR that see supressed and full auto fire, we shoot about 10-15K a year through our guns.

The RAS is old now. The URX 2 is better.  It should be URX or nothing.  All the new KAC rifles are comming with these.

I was referring to KAC AR's.  Stoner designed the DI for a 20 inch barrel.  It's the short barreled AR's that most people here are referring to.
If I was running a barrel less than 16 inches, I would choose a piston set up like LMT's MRP.  US SOCOM wasn't testing the HK 416 piston system
for kicks.  They wanted something that felt similar but more reliable for their shorter barrel DI M4's.

Barrel coming loose and "bent" gas rings? Come on, this is a maintenence issue not a design flaw.  Aren't there assembly guides with barrel installation instructions including proper torque for the barrel nut? Gas rings are a wear and tear item needing periodic replacement, as is the various springs in the rest of the rifle, etc?  You change the oil in your car every now and then right?

I didn't intend to 'call out' anyone - I'm sorry if it came across that way.

Could you post a picture of one of these 'bent' gas rings? I've simply never seen one and would like to know more about the phenomena.

Piston ARs are just another push to make us Commies. Leave the ARs ALONE!!!!!!!!!!!!

Funny thing is my LWRC doesn't have any of those problems he mentioned...maybe because they designed their system to avoid such problems. What an idiot, want those 20 seconds of my life back!

This topic gives me an idea.    Since the OP doesnt want his gas piston upper...hummm?    Im gonna take his place in line and place my order for an LMT MRP gas piston rifle, complete!

OK , in an effort to move this discussion away from DI-vs- piston which I think has been covered here more than enough; here are some thoughts. When he (Reed Knight) stated he would like to see a new caliber introduced he also meant a new cartridge design. We will be hard pressed to make a rifle which weighs less than the AR/DI system. A true weight savings will be achieved with a new cartridge design. Case telescope or caseless is the answer. I don't think a new gun will be more accurate than current ARs but we should not give up accuracy for a reliability increase. The other point is controllability which along with accuracy relates to hit probability. Piston guns that have a larger moving mass have inherently more recoil. Increasing the mass of the weapon can help this issue but is not a fair trade off in our eyes. The other issue is the buffer tube which has little design purpose on a Piston driven weapon due to the fact that the recoiling mass has been moves of the axis of the bore. .A shorter service life of the weapon is also not a desired trade off. The fact is there will be no ammo that will perform properly in both short and long barrels . A gun can be built to fire a common caliber in both a short and longer range configuration ; but a different cartridge will be needed. It does not matter what the caliber is 5.5mm,6mm,6.5mm or whatever. The botom line is to deal with the long term logistics of replacing the M-16 type rifle we need a gun that  is just as or more light weight, just as or more accurate, and more reliable than the current AR. The best way to achieve this is start with a clean sheet of paper  not just for the gun but the ammo as well. We have been compromising the original Stoner design since it's inception . We hack off the bbl and the buffer tube and then complain about it. It has served us well but we need to start from scratch to make the true weapon of the future.

KAC has made many piston designs. We will not follow trends if a true all around performance increase can not be achieved. If you notice our PDW does not use a stoner type bolt design, has rails in the upper and no buffer tube. I don't think it is the weapon of the future but it is a purpose built piston gun with AR controls/ergonomics .

The US Gov't and FN have spent millions and five plus years on the SCAR. If it is not the M-16 replacement then what a waste of time and money.

C. Reed Knight III(Trey) - KAC

It sounds as if allester666 is full of it to me. "On mission in Iraq" my ass.

In any case that is something that should have been caught by an armorer. If something was similarly amiss with a FAL, G3, AK, POF, whatever, and an armorer missed it, it would be the fault of the armorer, not the weapon. Stuff wears out, replace as necessary.

I had my own M4 fail on me twice. Both in combat!!!! One of my squad members almost died also when his M4 malfunctioned in the middle of a fire fight!!  Same BS! Sorry but all I have is piston guns now. And yes one has over 20,000 rounds through one of them! No breakages, no stoppage, and not one malfunction! And yes to no carrier tilt wear... More than I can say for the crap out there! Its a flawed design that almost got us killed a couple of times.  And yes our crap was clean!  When ever we go to any SWAT training now, there are always 3-6 M4's that are having problems. HMMMMM my piston rifles do not seem to?? I wonder why. Sorry but times change.. Just my .02!

Joined: Sep 2008

Posts: 13


mmmhmmmmm....

Watch if friend!!! If you don't know who is on the other side keep your comments to yourself.  If you want rebutt what I said, don't question where I have been and what I have done!  Thats seems to be the second VET you have questioned?????

I question bullshit. If it smells like bullshit, it is likely bullshit. And I'm not your friend.



Posted on 2/11:


Yeah, you must've sold that 10.5 LMT in the past 5 days, huh? Wait, let me guess, it's your "SWAT" weapon?

Well I guess we can meet in the desert if you seem to have a problem?? I guess me and some of my VET buddies, and Oh yea my SWAT guys can meet you out there also? Since you live in AZ, and you seem to question everything and know everything!!  It should not be a problem then, we can show you how real relaible weapons function..

And yes you are not a friend or would be worthy! , and yes that LMT has a piston on it!  And so do all the others...Like I said, thats all I run..

I spent a year in Iraq. And you're still full of shit. Oh, now your LMT has a piston on it, huh?

And for that matter, what police officer would want to take an online discussion into the real world? Perhaps one with a mental imbalance...Or perhaps a 14 year old kid talking from behind the impenetrable barrier of a computer screen...

WOW, me and my boys will be out in Buckeye, on the 7th of March!  Off of Miller and I-10, yes we will be the ones shooting with the night vision, and yes IR equipment also. Thats right civillians can't get IR! So if you need some lessons? We will be more than happy to help! We will be there all day and night, and yes just in case you ask no departments have any unknown distance ranges in the Phoenix area out to 1500 yds, so I take my guys out there, and yes the next question would be no departments have anything for that range, but they do. And its a .338 Lapua, and M107 for interdiction, and Airport security for aircraft glass penitration.. Anything else, we will see you out there??? No more talkyyy just do it.  

You realize that the military spent billions on the Crusader and Comanche and dropped them like hot potatoes?  Or the tens if not hundreds of millions spent on the XM-8, which wasn't field.  The mil spends money on projects that go no where all the time.

If I wanted a piston gun then I would get another FAL.  

Sorry to burst your bubble, but IR stuff comes up on the EE pretty often (legally), and I was issued it when I was in, and it's not worth the money to me.

Why would I want lessons anyway? Why would you offer? You really do seem to have some sort of issue...

What service and unit were you with? What MOS, when did you serve?

I'm wondering what this would mean for a purpose build Piston/Op-Rod setup that still makes use of the AR-15 bolt (you should know which weapon system I'm talking about).

Will it suffer from the same type of bolt stress issues (square wave impulse versus the more gradual/sinusoidal impulse curve of a gas impingement), or if that's even a pressing issue...



87GN - lay down the pwn hammer, bro.
I wasn't inclined to at first - but shotgun - I'd just walk away quietly while you can.  And use grammer check.  Wikipedia and snopes are your friend for next try.

Hahaha.

87GN for pres.

Sorry, posted in wrong topic.  Please ignore...

Colt has not been shy about stating that their piston driven systems are consumer driven, as it was with the 703, as it was with the SCAR-C 1020, as it likely is with the APC.  

"...Colt experimented with a piston driven version of their M16A1 rifle in the late 1960s....the piston system was deemed unnecessary by the U.S. Government and abandoned.  The government found no advantage to the use of the piston system in reliability compared to the finalized direct gas M16A1 rifle."  

"Applying the short-stroke tappet gas system has also been looked at in the mid-1980s: the RHINO system, as well as various parallel developments in the 1960s such as the AR-18."

"As recalled by Colt engineers who attended to SCAR Bidders Conference...the manufacturers were asked questions by the representatives [of SOCOM] such as, "Do you have a piston gun?" and "Would you consider making a piston gun?"  It was clear SOCOM wanted the piston system for their own reasons, so Colt built one.  The Colt SCAR type C would...be rated 'acceptable' along with the other two Colt entries"  

"...approach to the development of their final piston system to be sure their customers got the finest product the first time they offered it...The Colt piston system is also the only piston driven M16/AR platform to have completed and passed an Official U.S. Govt/SOCOM trial... go through several evolutionary changes before it would be sellable per Colt's standards."

"What is the real benefit of the LE1020 over the LE6920?  ...the extended rail system,"

Excerpts from Chris R. Bartocci, SAR Vol. 10 No. 10, July 2007

Colt does not seem to think its worth it, but they've given it a try because customers demanded it, several times, and continues to try to produce one that's acceptable.  It's not like they haven't got enough experience with the system to just shoehorn a piston into it, they're trying to make a piston system worth the effort, and failing.  The APC is just their most recent try, have you seen the 1020 on the shelf at the gunstore?  Remember, they're not going for "people will buy it," if the 1020 was released today, people would buy it and love it, and Colt knows that.

Consider the fact that the finalized SCAR was *not* an AR based piston system, it was a system that was designed from the ground up to use a piston, despite the fact that such designs were submitted.  

Oh, and hey, by the way, there may be more vets on this board than you might think.  If you are in fact a veteran, I would caution you about being so cavalier about waving your flag and trying to trash others.  Not to mention that being a veteran does *not* by any means make you a weapons expert.  I know a lot of veterans, many of my very close friends are veterans, and while they may be great guys, it doesn't mean that what they say is the be all and end all of weapons knowledge. Some of them are downright dumbshits when it comes to guns.  That doesn't mean they don't know what they're doing with them, and can't use them and maintain them, they can, and have, and I've trusted them to.  Doesn't mean I'd take their advice about anything other than how to use and maintain their weapons.  This goes quintuple for "SWAT guys."  Oh, and being a cop and reading SWAT magazine doesn't make you a SWAT officer, either.  

IMHO, piston is not particularly relevant to the AR15 weapon system.  Whether or not the AR is the best system out there is a topic for another day.  

~Augee

Take it outside you two..... or IM's... cause the rest of us don't really care...

As  to keep this thread on track..

I just read that article and my take..

I have been shooting AR Carbines for many years and have tens of thousands of rds, enough to  know that they work.'

I ran a T & E LWRC gas gun last year in a 3 day course and put 1400 rds thru it.. It was a 10.5" SBR and ran flawlessly.  
Yet I did nto have the urge to get one.
For a 16" or 14.5 " carbine or Middy, and your not in a Tier 1 unit that shoots high volumes, your well served with a GI.

If your running a SBR or happen to be a member of CAG and shoot 3000 rds in 6 day increments, then you may be better served with a piston.

The gas piston is not new or revolutionary...and there is no magic weapon that can just be abused and still expected to run reliability... (I know, hard to believe all you AK lovers..)

Funny how most of the gas piston advocates joined within the last year or so. Join date 2008 or 2009.

Love my piston and been here since the 90s under one name or another.  

The whole forward pressure of the DI preventing bolts from breaking... OMG that is SOOOO funny and even funnier people believe such nonsense!

LWRCs might have an issue here and ther but its not breaking bolts.  AR18s dont have a habit of breaking bolts in under 10K with a similar design.  Whats the gun that breaks bolts?  The M4 DI...  Jeeze a little common sense goes a long way guys.