piston heat reliability- why is the spring over the top of the hottest part of the barrel?

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[ARCHIVED THREAD] - piston heat reliability- why is the spring over the top of the hottest part of the barrel? (Page 1 of 2)

Posted: 6/27/2010 6:05:05 PM EDT

After blasting with the LWRC piston upper I notice the piston cup was not returning to the normal position(full forward). Part of the problem was the carbon build up, the other was the spring was worn out. The original spring has long since broken, and the replacement has shrunk in size, about a 1/4" when comapred to a new one. Not even that many rounds. The heat has done a number on it.

This lead to the upper running like shit, which got to me wondering why the hell is the spring on the piston upper over the hottest part of the barrel, like exactly the same place the m4's failed(but not the gas tube) in testing?

I have given up on the piston except for F/A and this has got me thinking it over again. They don't have any benefit with cans or SBRs IMO and I only really endorse them for F/A and keeping the heat down in the BCG. But my experience today made me wonder.

Is this a design flaw?

Posted: 6/27/2010 6:09:42 PM EDT

[#1]

Where else you gonna put it?

Your findings have basically mirrored everybody else's with the piston –– what's it supposed to fix for $500 +/- $100?

Posted: 6/27/2010 6:14:04 PM EDT

[#2]

The heat just goes somewhere else.

In my experience, there are very minor differences in bolt face temp compared to, say, gas block temp.

The gas block of a "piston" rifle will be hotter than the gas block of a "standard" rifle.

Posted: 6/27/2010 6:19:29 PM EDT

[#3]

That is why you have back up parts. And then you have back up parts for your back up parts. Shit happens.

Posted: 6/27/2010 6:26:54 PM EDT

[#4]

Or you just have a gas tube –– with no moving parts.

Priorities of work and basic rifle maintenance for the basic Ranger School student armed with the M16 hasn't changed since the M16A1 was standardized.

Shotgun the rifle, remove the bolt carrier group, wipe everything off (do NOT remove the bolt and firing pin, especially in the dark). Lube. Reassemble and function check. Load and Safe.

Really, how hard is that? You can do it in any clime whether you're a leg, paratrooper, mech, armor, SOF, or REMF.

You don't field strip the bolt if there's even a CHANCE you're going to lose something (like an extractor pin or firing pin retaining pin).

So why do I need a piston?

Posted: 6/27/2010 6:42:00 PM EDT

[#5]

This wasn't a post to bash the piston, it was a realization on may part. The BCG is cooler with a piston when you dump mags but its not cleaner with a can and SBR.

I guess it comes down to wearing out the spring in the extractor or a spring on the piston. A extractor spring is a lot easier to carry in the grip.

And for you that saw my long term post, I've worn out another FP for no reason.

Posted: 6/27/2010 7:38:13 PM EDT

[#6]

A different piston design places the transfer rod spring on the far end away from the gas block. Away from the heat which causes spring fatigue.

Posted: 6/27/2010 7:45:03 PM EDT

[#7]

Is the spring around the piston rod really necessary? I'd think the action spring would push the piston back into position when the bolt is fully closed. Is that not the case?

Posted: 6/27/2010 10:39:05 PM EDT

[#8]

Quoted:
Or you just have a gas tube –– with no moving parts.

Priorities of work and basic rifle maintenance for the basic Ranger School student armed with the M16 hasn't changed since the M16A1 was standardized.

Shotgun the rifle, remove the bolt carrier group, wipe everything off (do NOT remove the bolt and firing pin, especially in the dark). Lube. Reassemble and function check. Load and Safe.

Really, how hard is that? You can do it in any clime whether you're a leg, paratrooper, mech, armor, SOF, or REMF.

You don't field strip the bolt if there's even a CHANCE you're going to lose something (like an extractor pin or firing pin retaining pin).

So why do I need a piston?

Because you are going to actually shoot it and you get tired of broken bolt lugs, broken bolts at the cam pin slot, having to tweak buffers and springs from gas port erosion, early throat erosion, having to constantly lube bd the gun burns off the lube, having to deal with 1920 era metal finishes (Park), and just because you expect your duty weapon to have more than a 5K round useful service life.

Then there are suppressors...want to go there? You better have a piston gun or a lot of range time and various buffer weights.

DI guns are fine for 20 inch platforms but they sux for SBRs. Even Crane states that the MK 18 is a 5K round gun at best...

For many of us, 5K is two classes...that ain't much.

Posted: 6/28/2010 2:35:57 AM EDT

[#9]

Quoted:
Is the spring around the piston rod really necessary? I'd think the action spring would push the piston back into position when the bolt is fully closed. Is that not the case?

Actually it's not neccesary (AK does without it for eg.). However free floating (not attached to bolt carrier), spring driven rod moves forward while bolt and carrier still moves backward. This separates movement timig of bolt and carrier from op-rod and piston and reduces "moving masses" instability (forward movement of rod and piston counteracts rear movement of bolt and carrier) in bouth recoil and return to battery. This design was implemented into SVD by Mr. Dragunov to provide increased accuracy from semi auto DMR rifle (I think SVD is grandfather of all DMR rifles and actually of whole concept).

Posted: 6/28/2010 2:51:21 AM EDT

[#10]

radiated heat doesn't generally effect spring temper, the reduction in length is due to the spring continually becoming coil bound. i replaced the spring on my m6a2 with a different one and have seen better results but the weapon is overgassed to start with.

Posted: 6/28/2010 7:14:24 AM EDT

[#11]

That is how my POF upper works, no springs and so far no problems what so ever.

Posted: 6/28/2010 7:14:52 AM EDT

[#12]

The spring is not needed for the piston gun to run. Even if the spring was broken or shorten, the gun should run. The gun's recoil spring in the buffer tube pushes the carrier and piston system forward. The Osprey piston system does not have a spring and it runs fine. Don't think the spring is the problem.

Posted: 6/28/2010 8:03:13 AM EDT

[#13]

All piston AR designs are not the same, simple as that. There designed to run and function in a particular way, using the parts designed as best they can be used for a certain life. POF's with it's loose op rod is held in place and controls pressure put onto the rod in function by the piston and tube around it from the block. Adams and LWRC's are a piston cup/op rod and spigot design. I'm sure a proper seal needs to be maintained in a particular aspect of the timing to maintain proper function between the cup and spigot. Hence the extra spring on both. I'm not sure how much spacing if any LWRC maintains between the rear tip of the op rod and the carrier key when the cup is fully seated on the spigot, but Adams uses a certain amount to decrease the pounding the force of the key and buffer spring pressure puts on the rod to not damage it and cause the life to shorten.

What kind of steel their using for the spring I'm not sure though Adams is stainless from what it appears to me, same as the bolt spring. I'm not sure why it wouldn't be smarter to use chrome silicon instead since CS often has a higher heat tolerance and higher compression life by far. Chrome silicon can corrode easier, and I don't know about the rest of you, but I oil and grease my springs and the op rod on my Adams system all the way behind the cup into the receiver and everything but the bolt face in the receiver's action. There's no reason not to and lubrication decreases wear besides promoting smoother function.

Springs have a certain heat tolerance and compression life. You can't change that. There don't wear out from staying compressed alone, but the function of compression and decompression back and forth. Changing there temper from a certain level of heat can decrease life and having them rust or fight for function from more friction certainly doesn't help that I've found. In the end, you'll always need spares.

Posted: 6/28/2010 8:05:18 AM EDT

[#14]

Quoted:

Quoted:
Or you just have a gas tube –– with no moving parts.

Priorities of work and basic rifle maintenance for the basic Ranger School student armed with the M16 hasn't changed since the M16A1 was standardized.

Shotgun the rifle, remove the bolt carrier group, wipe everything off (do NOT remove the bolt and firing pin, especially in the dark). Lube. Reassemble and function check. Load and Safe.

Really, how hard is that? You can do it in any clime whether you're a leg, paratrooper, mech, armor, SOF, or REMF.

You don't field strip the bolt if there's even a CHANCE you're going to lose something (like an extractor pin or firing pin retaining pin).

So why do I need a piston?

Because you are going to actually shoot it and you get tired of broken bolt lugs, broken bolts at the cam pin slot, having to tweak buffers and springs from gas port erosion, early throat erosion, having to constantly lube bd the gun burns off the lube, having to deal with 1920 era metal finishes (Park), and just because you expect your duty weapon to have more than a 5K round useful service life.

Then there are suppressors...want to go there? You better have a piston gun or a lot of range time and various buffer weights.

DI guns are fine for 20 inch platforms but they sux for SBRs. Even Crane states that the MK 18 is a 5K round gun at best...

For many of us, 5K is two classes...that ain't much.

Yeah, Sinister doesn't spend any time at the range at all.

Posted: 6/28/2010 8:07:45 AM EDT

[#15]

After shooting with a NP3 treated BCG, I am convinced that coatings like this or NiBo essentially solve the "dirty" issue of a DI gun. My NP3 BCG literally requires just a wipe off with a paper towel to clean and can technically run without lube, though I don't do that. Bolt heat has been shown to basically be the same in DI and piston, and if you use the LMT enhanced bolt with the radiused lugs, a DI bolt has even longer life. The next evolution for DI guns will be easily adjustable gas blocks to conquer the gas port erosion issue. This would still keep the DI advantage of less moving parts and ease of part replacement.

Posted: 6/28/2010 8:17:00 AM EDT

[#16]

As the op said himself,

This wasn't a post to bash the piston, it was a realization on may part.

If your looking to DI troll move on.

Posted: 6/28/2010 9:28:13 AM EDT

[#17]

Quoted:

Because you are going to actually shoot it and you get tired of broken bolt lugs, broken bolts at the cam pin slot, having to tweak buffers and springs from gas port erosion, early throat erosion, having to constantly lube bd the gun burns off the lube, having to deal with 1920 era metal finishes (Park), and just because you expect your duty weapon to have more than a 5K round useful service life.

Then there are suppressors...want to go there? You better have a piston gun or a lot of range time and various buffer weights.

DI guns are fine for 20 inch platforms but they sux for SBRs. Even Crane states that the MK 18 is a 5K round gun at best...

For many of us, 5K is two classes...that ain't much.

Quoted:

As the op said himself,

This wasn't a post to bash the piston, it was a realization on may part.

If your looking to DI troll move on.

Hey now, I think that this stuff is a little uncalled for. I'm a firm DI believer, don't own a piston gun, and don't think there's any need for one, but I like to keep abreast of what's happening in the AR world, even with pistons so I lurk and sometimes contribute in the piston forum, so I try to be polite and help out when I can and otherwise read up. I don't think Sinister was being a DI troll, he was simply making a point, and I don't know if it's a persecution complex that some folks in this particular sub-forum have developed, but there's no need to jump on anyone who points out a potential benefit of using a DI versus a piston, even in a piston forum. Without being able to discuss such things, this becomes nothing more than a fan boy forum, you needn't get defensive, nor inflammatory when someone even mentions DI.

The fact that Joe can be dumb and will often lose things is not a wholly unheard of concept, and since the beginning it has been one of the reasons I have been against the adoption of any kind of piston conversion for military use, for however little my opinion counts on the matter, I do know, however, that the last time I drew 240s, supply tried to give me two that were missing the gas regulator caps, and god knows what had happened to them, luckily I could tell by a glance that there was something off, and I refused them, otherwise, the parts would have come out of my pocket, so the issue of parts loss during field maintenance, at least in a military environment is a big one to me.

And LockingBlock, your post is not borne out at all by a great deal of experience, both my own personal, and attested to by many knowledgeable professionals who run DI platforms with, egad - parkerized steel parts through many multiple classes, in SBR form, and suppressed. If you have a preference, you're welcome to it, and I respect that you prefer piston operated ARs, but it does not give you the right to spew misinformation as if it's hard and proven fact, nor to belittle those who disagree with you.

~Augee

Posted: 6/28/2010 10:28:48 AM EDT

[#18]

Quoted:

Quoted:

Because you are going to actually shoot it and you get tired of broken bolt lugs, broken bolts at the cam pin slot, having to tweak buffers and springs from gas port erosion, early throat erosion, having to constantly lube bd the gun burns off the lube, having to deal with 1920 era metal finishes (Park), and just because you expect your duty weapon to have more than a 5K round useful service life.

Then there are suppressors...want to go there? You better have a piston gun or a lot of range time and various buffer weights.

DI guns are fine for 20 inch platforms but they sux for SBRs. Even Crane states that the MK 18 is a 5K round gun at best...

For many of us, 5K is two classes...that ain't much.

Quoted:

As the op said himself,

This wasn't a post to bash the piston, it was a realization on may part.

If your looking to DI troll move on.

Hey now, I think that this stuff is a little uncalled for. I'm a firm DI believer, don't own a piston gun, and don't think there's any need for one, but I like to keep abreast of what's happening in the AR world, even with pistons so I lurk and sometimes contribute in the piston forum, so I try to be polite and help out when I can and otherwise read up. I don't think Sinister was being a DI troll, he was simply making a point, and I don't know if it's a persecution complex that some folks in this particular sub-forum have developed, but there's no need to jump on anyone who points out a potential benefit of using a DI versus a piston, even in a piston forum. Without being able to discuss such things, this becomes nothing more than a fan boy forum, you needn't get defensive, nor inflammatory when someone even mentions DI.

The fact that Joe can be dumb and will often lose things is not a wholly unheard of concept, and since the beginning it has been one of the reasons I have been against the adoption of any kind of piston conversion for military use, for however little my opinion counts on the matter, I do know, however, that the last time I drew 240s, supply tried to give me two that were missing the gas regulator caps, and god knows what had happened to them, luckily I could tell by a glance that there was something off, and I refused them, otherwise, the parts would have come out of my pocket, so the issue of parts loss during field maintenance, at least in a military environment is a big one to me.

And LockingBlock, your post is not borne out at all by a great deal of experience, both my own personal, and attested to by many knowledgeable professionals who run DI platforms with, egad - parkerized steel parts through many multiple classes, in SBR form, and suppressed. If you have a preference, you're welcome to it, and I respect that you prefer piston operated ARs, but it does not give you the right to spew misinformation as if it's hard and proven fact, nor to belittle those who disagree with you.

~Augee

Negative. The Ops question to me are about the spring and it's location. Not about people's feelings on DI to Piston and how they feel it's unnecessary. This kind of shit is not wanted here. It's a pointless argument that's been argued over and over on many forum besides Arf. Unless someone specifically asks about it, this applies and many people besides me don't want to see this crap. It's trolling and distracts from the actual point of the thread.

Forum rules

Posted: 6/28/2010 10:54:34 AM EDT

[#19]

Roger, I get that, and I have no input in it so I stayed out of it. That being said, unless you're going to wave the CoC flag at every thread that gets de-railed, no matter what the subject and what the subsequent de-railment (how many threads exactly end up talking about exactly what the OP asked?), but I nevertheless felt that the comments about DI trolling were uncalled for, they were not about "let's get this back on the OP's topic," they were about - "how dare you spout DI propaganda in our forum!" which I don't believe they did.

Regardless, no harm done, and no offense taken, and in the interests of not yanking this thread further off topic, I'll leave this one lie.

~Augee

Posted: 6/28/2010 11:31:16 AM EDT

[#20]

Regarding the "design flaw" question raised by the OP.. Seems to me that the solution to this problem could be the PWS long stroke system. I don't think the buffer spring would ever die like this one has. Just a thought

Posted: 6/28/2010 2:08:13 PM EDT

[#21]

OP, contact LWRC.

I'm curious to see what they say.

-Ed

Posted: 6/28/2010 3:33:07 PM EDT

[#22]

in answer to the op's original question, the spring and its placement are not a design flaw. with this particular short-stroke design the spring is there to arrest the rearward motion of the op-rod once it has completed its power stroke and return it to the original position closing the gas system in the process. without the return spring you would need some sort of mechanical means of stopping the op-rod before the piston blows out of contact with the cylinder. as i mentioned above, radiated heat rather than direct heat has a very limited effect if any on spring temper (think of springs on the valves in motors for example) so the shortnening of the spring is a direct result of it being coil bound by repeated over compression - this likely happens within the first few rounds after the spring is replaced. i have no idea how many rounds you have on this but gas port erosion could be an issue in over gassing the spring.

Posted: 6/28/2010 6:01:18 PM EDT

[#23]

Quoted:
OP, contact LWRC.

I'm curious to see what they say.

-Ed

Its already been back for other stuff, I have already posted the 40k test and all the stuff I have broken. Its in the archives

They sent a bag of springs when the upper came back last time.

There are very few people that have blasted that much, plus also have other DI uppers with 5 digit numbers on them.

For the guys with a couple thousand on a gun and are attesting to the durability, I would reconsider.

Posted: 6/28/2010 6:37:01 PM EDT

[#24]

you know their springs are not right?

Posted: 6/28/2010 7:08:49 PM EDT

[#25]

use the osprey piston, no springs, mine works well

Posted: 6/28/2010 8:03:15 PM EDT

[#26]

Quoted:
After blasting with the LWRC piston upper I notice the piston cup was not returning to the normal position(full forward). Part of the problem was the carbon build up, the other was the spring was worn out. The original spring has long since broken, and the replacement has shrunk in size, about a 1/4" when comapred to a new one. Not even that many rounds. The heat has done a number on it.

This lead to the upper running like shit, which got to me wondering why the hell is the spring on the piston upper over the hottest part of the barrel, like exactly the same place the m4's failed(but not the gas tube) in testing?

I have given up on the piston except for F/A and this has got me thinking it over again. They don't have any benefit with cans or SBRs IMO and I only really endorse them for F/A and keeping the heat down in the BCG. But my experience today made me wonder.

Is this a design flaw?

But not the gas tube? lol... yeah, right!

Posted: 6/28/2010 8:09:11 PM EDT

[#27]

Quoted:
Or you just have a gas tube –– with no moving parts.

Priorities of work and basic rifle maintenance for the basic Ranger School student armed with the M16 hasn't changed since the M16A1 was standardized.

Shotgun the rifle, remove the bolt carrier group, wipe everything off (do NOT remove the bolt and firing pin, especially in the dark). Lube. Reassemble and function check. Load and Safe.

Really, how hard is that? You can do it in any clime whether you're a leg, paratrooper, mech, armor, SOF, or REMF.

You don't field strip the bolt if there's even a CHANCE you're going to lose something (like an extractor pin or firing pin retaining pin).

So why do I need a piston?

I love this web-site!

Posted: 6/29/2010 12:04:36 PM EDT

[#28]

I second the Osprey 416 no springs to wear out so nothing is effected by heat fatigue.

Posted: 6/29/2010 2:51:58 PM EDT

[#29]

Quoted:
you know their springs are not right?

what do you mean?

Posted: 6/29/2010 2:55:04 PM EDT

[#30]

Quoted:

But not the gas tube? lol... yeah, right!

you mean getting too hot?

well the m4 test blew out a barrel while the gas tube continued to work-care to explain why?

the barrel retains more heat than a gas tube, yes you can get tubes red hot, but with a can the barrel will go before the tube.

a gas tube can get hot/cold, if a spring does this it will lose its tension

so whats your point?

Posted: 6/29/2010 3:12:15 PM EDT

[#31]

Looking at the Adams Arm piston spring, it doesn't seem to really do much besides prevent it from rattling around and helping it return more smoothly. If that spring failed, the bolt carrier and buffer spring would push that piston back home.

It's interesting to see the barrel run cooler with the piston system.

Posted: 6/29/2010 4:28:38 PM EDT

[#32]

Quoted:

Quoted:

But not the gas tube? lol... yeah, right!

you mean getting too hot?

well the m4 test blew out a barrel while the gas tube continued to work-care to explain why?

the barrel retains more heat than a gas tube, yes you can get tubes red hot, but with a can the barrel will go before the tube.

a gas tube can get hot/cold, if a spring does this it will lose its tension

so whats your point?

Take a look at this:
www.pof-usa.com/pdf_files/p-4161000endurancetest.pdf

Its a torture test between the POF and the DI gas system.

Gas tubes melt:
video.nytimes.com/.../1247466496255/m-4-firing-test.html
In this high speed video you see a M4 firing like 900 rounds then its on fire, but at the end you see it has to be charged for each shoot and thats becuase the gas tube has melted.

I've seen two gas tubes melt. One in a M16A4 and in a M4.

The POF system runs without the spring on the op rod, but I think the even a system with the spring will still run with the lost of its tension.

later

Posted: 6/29/2010 7:54:57 PM EDT

[#33]

Quoted:

Its a torture test between the POF and the DI gas system.

okay I guess you carry 900 rounds and have a F/A weapon?

Why would you use such a stupid example to back a ridiculous claim

Now if it had been say 300 rounds and it failed, well maybe, just maybe it could be a concern.

Posted: 6/30/2010 6:46:01 AM EDT

[#34]

Quoted:

Quoted:

Its a torture test between the POF and the DI gas system.

okay I guess you carry 900 rounds and have a F/A weapon?

Why would you use such a stupid example to back a ridiculous claim

Now if it had been say 300 rounds and it failed, well maybe, just maybe it could be a concern.

Ridiculous? The "DI" failed at 300rds....and its nice for me to know your limitation

Posted: 6/30/2010 10:51:37 AM EDT

[#35]

Quoted:

Ridiculous? The "DI" failed at 300rds....and its nice for me to know your limitation

thats a hell of test, especially the explanation of how it failed, ammo was wolf, they already said the feed tower was broken was it the same mag. It could have been a failure of the mag, but who knows

If i want to shoot 500 rounds continuously I have a 21 for that.If that doesnt work I will get the m2,

The point is does this test, or really any test than most manfs put forth to back up claims reflect reality at all?

does anyone carry 9 beta mags, will you ever really dump that many round continuously.

If people make their decisions based of expectations they can never meet, then why waste money?

I have dumped 2 beta mags through a DI and piston system and they both worked, 2 betas is my limitation becuase thats all i have in 223.

Posted: 6/30/2010 8:16:58 PM EDT

[#36]

Quoted:

Quoted:

Ridiculous? The "DI" failed at 300rds....and its nice for me to know your limitation

thats a hell of test, especially the explanation of how it failed, ammo was wolf, they already said the feed tower was broken was it the same mag. It could have been a failure of the mag, but who knows

If i want to shoot 500 rounds continuously I have a 21 for that.If that doesnt work I will get the m2,

The point is does this test, or really any test than most manfs put forth to back up claims reflect reality at all?

does anyone carry 9 beta mags, will you ever really dump that many round continuously.

If people make their decisions based of expectations they can never meet, then why waste money?

I have dumped 2 beta mags through a DI and piston system and they both worked, 2 betas is my limitation becuase thats all i have in 223.

If people make their decisions based of expectations they can never meet, then why waste money?
I'm not to sure what you mean by that, but I would hope that I wouldn't need to dump that kind of fire power down range but if I find myself in that kind of a situation its reassuring to know that the POF is up to the task.

The point is does this test, or really any test than most manfs put forth to back up claims reflect reality at all?
The reality of their reliability.

Posted: 6/30/2010 9:28:29 PM EDT

[#37]

The point of that test is to show which can stand up to more. For people who want the toughest, most reliable gun possible for whatever they may need to put it through knowing life doesn't always play by the rules.

Posted: 7/1/2010 1:27:39 AM EDT

[#38]

Quoted:

The point of that test is to show which can stand up to more. For people who want the toughest, most reliable gun possible for whatever they may need to put it through knowing life doesn't always play by the rules.

+1

As we use to say here "on battlefield value of cosine can even reach 3". Nice theories that "I'll never shoot 300 rounds in a row from assault rifle" usually do not live long under fire. Pistons were introduced to ARs for use of warriors not for range plinking.

Posted: 7/1/2010 1:37:54 AM EDT

[#39]

Quoted:
Pistons were introduced to ARs for use of warriors not for range plinking.

But almost all the pistons on ARs are used by plinkers and not warriors. Having been in a couple of dozen fire fights in the last several years, Other than when a unit is doing a break contact/mad minute will an M16 series weapon be fired in that manner and even with that there is still normally a break to in fire to move. But the problem is you are using a rifle/carbine in the role of a light machine gun.

Posted: 7/1/2010 5:23:03 AM EDT

[#40]

Quoted:

Quoted:
Pistons were introduced to ARs for use of warriors not for range plinking.

But almost all the pistons on ARs are used by plinkers and not warriors. .

Make it "But almost all the pistons on ARs in US are used by plinkers and not warriors". But there is quite big bunch of those outside of US. All US made "piston ARs" are just local "niche market" comparing to worlwide penetration of one piston AR design massivelly adopted by special forces, elite units and even whole armies (and used on real battlefield by at least 3 countries - US and Poland in offensive operations and Norway in stabilisation mission). And with M27 this trend might penetrate into US military forces as well.

BTW For breaking contact everything is good if you have active LMG on your team. But it's even better if every rifle can assume IAR role if needed. Added safety, versality and tactical flexibility.

Posted: 7/1/2010 6:22:52 AM EDT

[#41]

Don't forget to include the Taiwanese T65 series. That gun has been in use for thirty years, in one form or another, and is in use by several countries.

Posted: 7/1/2010 6:35:42 AM EDT

[#42]

Quote:The spring cup prevents the operating rod spring from deformation from compressing to solid during operation,and also acts as a stop against the collar of the operating rod in the unlikely event the spring should fail. Even if the spring should fail, the system will continue to operate as the operating parts will be pushed forward into battery by the bolt group's going into battery within the upper receiver. The LWRC uses about 1mm of float in the operating parts. That is, the operating parts will move rearward approximately 1mm before the tip of the operating rod contacts the anvil on the bolt carrier. Even if the operating rod spring breaks or weakens or the piston cup is so fouled that the resistance is more than the operating rod spring can overcome, the bolt group's going into battery will push the operating parts back into battery. This level of redundancy does not exist on many of the other gas-piston conversions by other manufacturers. Many of these other designs rely solely on the proper function of the operating rod spring and will not function if that single component is not functioning properly.

http://www.expeditionexchange.com/lwrc/

Posted: 7/1/2010 8:11:28 AM EDT

[#43]

Quoted:

The point of that test is to show which can stand up to more. For people who want the toughest, most reliable gun possible for whatever they may need to put it through knowing life doesn't always play by the rules.

so you carry 9 betas and plan to dump in at once? I dont give a shit what life throws at you you will not be walking around with 9 betas, even in a static position

Do you have solid tires on your car? They are better and will last longr than normal tires. Why not have them?

Your retoric to support your argument is outstanding.

The point being

1, I find that the test is suspect with the limited info it presents about the failure and no information on the barrel differences- which if they did that test in the way it is written, I find it hard to belive the barrel did not sustain damage.

2. Basing a purchase decision on a limit that is not realistic is retarded. It is the same as a soccer mom driving a H3. If you want to represent that class of people then so be it.

Posted: 7/1/2010 11:13:37 AM EDT

[#44]

Quoted:

Quoted:

The point of that test is to show which can stand up to more. For people who want the toughest, most reliable gun possible for whatever they may need to put it through knowing life doesn't always play by the rules.

so you carry 9 betas and plan to dump in at once? I dont give a shit what life throws at you you will not be walking around with 9 betas, even in a static position

Do you have solid tires on your car? They are better and will last longr than normal tires. Why not have them?

Your retoric to support your argument is outstanding.

The point being

1, I find that the test is suspect with the limited info it presents about the failure and no information on the barrel differences- which if they did that test in the way it is written, I find it hard to belive the barrel did not sustain damage.

2. Basing a purchase decision on a limit that is not realistic is retarded. It is the same as a soccer mom driving a H3. If you want to represent that class of people then so be it.

If that makes you feel better bud. To me your a guy who simply just doesn't get it and no amount of explaining could change that I'm sure. Cheers.

Posted: 7/1/2010 4:17:57 PM EDT

[#45]

Quoted:

Quoted:

The point of that test is to show which can stand up to more. For people who want the toughest, most reliable gun possible for whatever they may need to put it through knowing life doesn't always play by the rules.

so you carry 9 betas and plan to dump in at once? I dont give a shit what life throws at you you will not be walking around with 9 betas, even in a static position

Do you have solid tires on your car? They are better and will last longr than normal tires. Why not have them?

Your retoric to support your argument is outstanding.

The point being

1, I find that the test is suspect with the limited info it presents about the failure and no information on the barrel differences- which if they did that test in the way it is written, I find it hard to belive the barrel did not sustain damage.

2. Basing a purchase decision on a limit that is not realistic is retarded. It is the same as a soccer mom driving a H3. If you want to represent that class of people then so be it.

If that makes you feel better bud. To me your a guy who simply just doesn't get it and no amount of explaining could change that I'm sure. Cheers.

+100 Its sad to see some of the traditional guys come to this.
Now hes calling us soccer Moms in SUV.

Posted: 7/1/2010 6:21:46 PM EDT

[#46]

Quoted:

Quoted:

The point of that test is to show which can stand up to more. For people who want the toughest, most reliable gun possible for whatever they may need to put it through knowing life doesn't always play by the rules.

so you carry 9 betas and plan to dump in at once? I dont give a shit what life throws at you you will not be walking around with 9 betas, even in a static position

Do you have solid tires on your car? They are better and will last longr than normal tires. Why not have them?

Your retoric to support your argument is outstanding.

The point being

1, I find that the test is suspect with the limited info it presents about the failure and no information on the barrel differences- which if they did that test in the way it is written, I find it hard to belive the barrel did not sustain damage.

2. Basing a purchase decision on a limit that is not realistic is retarded. It is the same as a soccer mom driving a H3. If you want to represent that class of people then so be it.

If that makes you feel better bud. To me your a guy who simply just doesn't get it and no amount of explaining could change that I'm sure. Cheers.

http://www.ar15.com/archive/topic.html?b=3&f=118&t=370094

I think it's safe to say that his opinion carries weight...but, of course, your rhetoric outweighs his experience.

Posted: 7/1/2010 7:12:01 PM EDT

[#47]

Quoted:

Quoted:

The point of that test is to show which can stand up to more. For people who want the toughest, most reliable gun possible for whatever they may need to put it through knowing life doesn't always play by the rules.

so you carry 9 betas and plan to dump in at once? I dont give a shit what life throws at you you will not be walking around with 9 betas, even in a static position

Do you have solid tires on your car? They are better and will last longr than normal tires. Why not have them?

Your retoric to support your argument is outstanding.

The point being

1, I find that the test is suspect with the limited info it presents about the failure and no information on the barrel differences- which if they did that test in the way it is written, I find it hard to belive the barrel did not sustain damage.

2. Basing a purchase decision on a limit that is not realistic is retarded. It is the same as a soccer mom driving a H3. If you want to represent that class of people then so be it.

If that makes you feel better bud. To me your a guy who simply just doesn't get it and no amount of explaining could change that I'm sure. Cheers.

http://www.ar15.com/archive/topic.html?b=3&f=118&t=370094

I think it's safe to say that his opinion carries weight...but, of course, your rhetoric outweighs his experience.

I swear some of you guys crack me up on here. Like your outlooks, opinions and experience is all that matters and no one elses does so they have to agree with you. It remind me of little kids stumping their feet with their arms crossed, frowning when they don't get their way.

Try to play nice.

Posted: 7/2/2010 12:43:32 AM EDT

[#48]

Quoted:

Quoted:
Pistons were introduced to ARs for use of warriors not for range plinking.

But almost all the pistons on ARs are used by plinkers and not warriors. .

Make it "But almost all the pistons on ARs in US are used by plinkers and not warriors". But there is quite big bunch of those outside of US. All US made "piston ARs" are just local "niche market" comparing to worlwide penetration of one piston AR design massivelly adopted by special forces, elite units and even whole armies (and used on real battlefield by at least 3 countries - US and Poland in offensive operations and Norway in stabilisation mission). And with M27 this trend might penetrate into US military forces as well.

BTW For breaking contact everything is good if you have active LMG on your team. But it's even better if every rifle can assume IAR role if needed. Added safety, versality and tactical flexibility.

The H&K is used by very few compared to the millions of M16 used by both the US military, other worlds militaries and in actual usage. I have read all the info put out, including the stuff not put out to the public, about the M27 (actually name of the IAR) and I don't know how they came to the conclusions they did.

Posted: 7/2/2010 4:27:19 AM EDT

[#49]

Quoted:

Quoted:
Pistons were introduced to ARs for use of warriors not for range plinking.

But almost all the pistons on ARs are used by plinkers and not warriors. .

Make it "But almost all the pistons on ARs in US are used by plinkers and not warriors". But there is quite big bunch of those outside of US. All US made "piston ARs" are just local "niche market" comparing to worlwide penetration of one piston AR design massivelly adopted by special forces, elite units and even whole armies (and used on real battlefield by at least 3 countries - US and Poland in offensive operations and Norway in stabilisation mission). And with M27 this trend might penetrate into US military forces as well.

BTW For breaking contact everything is good if you have active LMG on your team. But it's even better if every rifle can assume IAR role if needed. Added safety, versality and tactical flexibility.

The H&K is used by very few compared to the millions of M16 used by both the US military, other worlds militaries and in actual usage. I have read all the info put out, including the stuff not put out to the public, about the M27 (actually name of the IAR) and I don't know how they came to the conclusions they did.

I tought pisiton ARs for plinking vs piston AR for warriors. If you want to compare number of 416 to number of M16s fielded - then I beat it with number AK/AK74 and clones (Galil, Valmet, FNC, Beryl, etc. etc) fielded

Pointless, isn't it?

As to IAR programme I think most of confusion goes from mismatching concept of LMG (Light Machine Gun) and AR (Automatic Rifle). In the past bouth sides od steell curtain opted for "Universal Machine Gun" - when something is universal it means it's equally bad for every role - like "all-season tyres" -> only good for California. M249 SAW is "UMG" -> it was used as AR (too big, too heavy, not accurate, not reliable in this role), as LMG (here fits good!) and MG (caliber used not so good for fixed, defensive positions). In role of MG M240B works better and is used. What M27 IAR is supposed to achieve is not replace M249 SAW but only replace/append in role of AR (Automatic Rifle). Look the numbers - 4000+ M27 is to replace just 2000 M249. What it means? 2+ M27 in place of 1 M249. I may live in Poland but we fight hand to hand with US and we know that last thing to tell is USMC is not knowing what they are doing. Especially that all IAR program started several years ago with first experiments in this area.

Going to original question - M249 uses piston for high volumes of fire - looks like properly designed piston system gives enought heat reliability. On the other hand - is there any DI MG/LMG/AR fielded?

Posted: 7/2/2010 4:34:47 AM EDT

[#50]

Quoted:
Or you just have a gas tube –– with no moving parts.

Priorities of work and basic rifle maintenance for the basic Ranger School student armed with the M16 hasn't changed since the M16A1 was standardized.

Shotgun the rifle, remove the bolt carrier group, wipe everything off (do NOT remove the bolt and firing pin, especially in the dark). Lube. Reassemble and function check. Load and Safe.

Really, how hard is that? You can do it in any clime whether you're a leg, paratrooper, mech, armor, SOF, or REMF.

You don't field strip the bolt if there's even a CHANCE you're going to lose something (like an extractor pin or firing pin retaining pin).

So why do I need a piston?

Yep.

To design the AR correctly with piston, the gas system should be higher (like AK) with newly designed upper to accomodate it.

Might as well just get a SIG 55X.

[ARCHIVED THREAD] - piston heat reliability- why is the spring over the top of the hottest part of the barrel? (Page 1 of 2)

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