ATTENTION: LWRCI Piston Gun Owners

[BPowderkeg]

upon cleaning my LWRCI M6, which i do after about 3,000 rounds i discovered the op rod spring was broken in two places, i then inspected another M6 and that spring was broken in 5 places, yet the gun functioned, i called LWRCI and got one of their technicians, i told him of my problem, what he said really kinda surprised me, he said, "that was a common problem and the spring should be replaced after every 3,000 to 5,000 rounds, we are working to replace the spring with an upgrade"

the spring is a flat coil spring, http://www.lwrci.com/p-79-piston-ret....aspx#inf-tabs in my OPINION that is a bad idea, flat coil springs are a disaster waiting to happen, (again, my OPINION !!) the manufacturing process for a flat coil spring makes them susceptible to failure, machining marks make them weak their entire length, round coil springs are far superior to flat ones, especially if they are shiny/bright (i hope you know what i mean).

soooo.., if any of you own an LWRCI piston gun i highly recommend that you inspect your op rod spring, trust me, the gun may still function with a broken spring, the last shooting session (8 days ago) with the one with a broken spring in 5 places, i discovered a "C" clip looking piece of metal on the bench, put it in my range box thinking it may have already been there and didn't give it any thought till i was cleaning the other rifle.

one final note, i do not believe we should have to buy another spring, as it is a design flaw that LWRCI knew about simply because they recommend it be replaced after 3,000 - 5,000 rounds, THAT is NOT reliability for a firearm that someone is using to defend their life with !!

[globalsmack]

Most other pistons on the market don't even use a spring.

[Tempest 455]

Interesting. Good thing I have less than 500 rounds on mine. I can wait a while before I worry about it.

[Uncle Malice]

Weird. That seems silly.

My only piston gun is the Ruger SR556 and it's complete system is designed to never need to be taken apart at all. The manual says that you should never need to disassemble it for any reason other than the plug up in the front where all the carbon accumulates.

After thousands of rounds and never having a single failure of any kind... it seems like it's on the right track to being true.

I thought LWRC was supposed to be some extremely rugged piston design? One of the best? Replacing a spring every 5k rounds seems silly to me...

[Nitesites]

Kind of suprising but I wouldn't fret just yet. Give them a minute and see what they do to correct it.

[CarlosDJackal]

Interesting. I will check out my rifles. I have a 10.5" M6A1 that has over 14,000-rounds whose spring I have only replaced once. The only issue with it was that it was much shorter than a new one.

[tirod]

This reflects the concept that somehow we can buy weapons that don't need a lot of maintenance. Their mechanisms, despite what the user might think, require periodic inspection, cleaning, repair, etc.

If a gun is required to be ready for use to defend one's life, the military standard is to check it and clean it DAILY. That's the standard in the field, in combat.

Basically, waiting every 3,000 rounds to look inside is saying you're willing to trust someone else's judgment about YOUR life. No doubt the biggest part of the situation is that your expectation has been crushed. No, they didn't meet your standard after all.

No gunmaker can, ever. It's a false hope. If you don't inspect a life and death duty weapon regularly, even daily, that's exactly how much emphasis is really being placed on it. Don't put the burden on them when it's your life.

Buying into a weapon that is sold on the general concept that it stays cleaner longer just means you fall into the trap of not checking it as often as needed. Had the rifle been shotgunned, wiped down, and a minute taken to look it over every time it was shot, then that little circlip of spring would have meant something a lot sooner.

Ignoring it for weeks is it's own reward.

If anything, the Army already has a challenge in that the standard DI M4 and M16A2 require spring changes regularly based on round count, but no way to record it. So the guns are shot until they fail, at which time it's a problem. Not a good system, and entirely why they want a round counter on them. It's been suggested by others that action springs, extractors and springs, even bolts be changed on 5k and 10k intervals. Knowing that, it's no surprise to hear of a different design suffering the same problem. It's really all about springs - they can and will fail. You can't rely on them perpetually.

It's up to the user to understand that and act accordingly. There is no maintenance free gun.

[Willie Lowman]

In before the DI vs piston nonsense!


LWRCI should have a recall on those springs and replace them with the new springs. If they can't do that, at least publish that the springs must be replaced every 3,000 rounds in the literature that comes with the rifle.

[Crow Hunter]

Seems reasonable.

The Glock recoil spring assembly is a flat wound spring and it is recommended to change at 5,000 rounds or sooner, depending on caliber and what rounds you are shooting. I got one of mine up to almost 7,000 before I started getting a shotgun pattern from unpredictable unlocking.

Tirod is right.

Springs DO NOT last forever. Eventually they will wear out/break. Those that cycle the most, are the ones that will wear out the quickest.

Changing a spring at 3,000 rounds is pretty cheap insurance in my opinion.

[Fishbed77]

The Glock recoil spring assembly is a flat wound spring and it is recommended to change at 5,000 rounds or sooner, depending on caliber and what rounds you are shooting.

I was thinking the same thing. Recoil springs need to be changed for just about any pistol at the 5,000 round mark. No surprise that springs would have to be changed for any other firearm that compresses them every firing cycle.

[BPowderkeg]

Willie Lowmansays:
LWRCI should have a recall on those springs and replace them with the new springs. If they can't do that, at least publish that the springs must be replaced every 3,000 rounds in the literature that comes with the rifle.

i agree !! i love my piston guns, i wish they had made note of the spring failure possibility after 3,000 - 5,000 rounds in their owners manual. yes ! they should do a "recall" on the springs and offer the "new" spring at no charge.

i do not know what may have changed in the spring manufacture, but i have one of the very first piston guns, that spring is still intact with about 10,000 rounds thru it.

tirod,
"Basically, waiting every 3,000 rounds to look inside..." i do check the "inside" after every shooting session with a 225 lumen flashlight thru the openings of the rail handguard and found no problem, it was the next shooting session (280 rnds.) that the spring failed that is when i found the "C" clip looking piece, but only clean after 3,000 rounds as there is little if any "REAL" cleaning is necessary. do you own an LWRCI rifle/carbine ? if not, then i recommend you buy one, they are a great rifle/carbine except for that damned spring.

Crow Hunter,
"Springs DO NOT last forever." sir, i am going to have to call BS ! on that ! i have a .22 rifle that is 117 years old i have had it since i was 13 y.o., it has the original springs, it has had well over 20,000 (maybe more) rounds thru it, i also have a .54 cal. Flintlock rifle that was made around 1840ad, i have shot it around 2,500 rounds, springs are still very stiff, plus the rifle is very accurate, i won several "split a ball and break two clay targets" matches during my "Mountain Man" days, but i still revert to my good old Colt AR-15 SP-1...., not too often any more since i went "TACTICOOL"

[Crow Hunter]

sir, i am going to have to call BS ! on that ! i have a .22 rifle that is 117 years old i have had it since i was 13 y.o., it has the original springs, it has had well over 20,000 (maybe more) rounds thru it, i also have a .54 cal. Flintlock rifle that was made around 1840ad

Do those springs have to operate at elevated temperatures over a very hot barrel and deal with the same level of compressive fatigue that your piston spring does?

ALL springs have a finite life and will eventually fail due to fatigue on a molecular/metallurgical level. Heat accelerates this fatigue, large amounts of movement also accelerates it. A spring that only moves 1/10th of it's free length with every cycle will live much longer than the same spring that goes from fully compressed to almost free length with every cycle.

Design characteristics also have alot to do with it. A spring that holds a rear sight in, or that drives a hammer can be designed to last MUCH longer than a spring that has to be used a buffer. You can't put a "over designed" spring into a buffer. If you make the spring rate too high, it won't act as a buffer, it will keep whatever you are buffering from working correctly.

Just because they are springs, doesn't mean they are the same.

ETA: I am not saying that there isn't a serious problem with the LWRC design or that there aren't alternatives with improved characteristics. Only that a similar designed spring has a similar life and I don't think it is a bad spring. Marginal design maybe, but I don't think you have a bad spring.

[tirod]

Springs fail. Some springs fail sooner than others because of their working environment. Others fail simply because the cheaper spring was chosen to meet a price point - and sell more springs. Proprietary designs are sometimes deliberately under spec'd to generate sales in the future - spare parts to replace those after their service life is obviously expired.

No machine can operate infinitely. It takes maintenance, and parts must be changed out to maintain sealing, proper operating clearances, etc, or it becomes damaged beyond repair.

If anyone buys into a marketing campaign that suggests modifying a design will improve it's long term longevity without maintenance, please point out the reproducible and scientific tests pointing out it's success. I'll buy it, too.

Buying into the "piston means I clean it less" philosophy means trusting their design criteria and doing less maintenance. I don't see that as any advantage in a "life and death" gun. If anything, DOD already set the standard dealing with guns made on contract - in combat, you check them daily, and you check it all.

The M16 is yet unsurpassed in design for disassembly to check critical components on a daily basis, rapidly, with a minimum of fuss. Compared to the M1 and M14, it's almost miraculously easy to shotgun and pull the piston carrier out in seconds. The action spring isn't subjected to high heat levels. The parts are all visible within literal seconds to inspect.

Why this is continually ignored and demeaned is remarkable. Then others come along with $400 "improvements" which in this case highlight the system flaw in their concept. Not being able to check all the parts every time you shoot it has led to not knowing components failed and needed replacement.

I'm not whitewashing it to make it more palatible, it's obvious that selling the concept you can abuse the weapon with less maintenance is simply setting up the user for problems or even catastrophic failure - that following common practice would prevent.

Tear it down after every shoot and inspect it. All too soon you'll find something that needs replacement. It's not a matter of time as much as quantity of ammo. It will happen.

You can't get 350,000 miles out an engine that is constantly neglected, it takes careful and continuous maintenance to do it.

[Tempest 455]

Springs fail. Some springs fail sooner than others because of their working environment. Others fail simply because the cheaper spring was chosen to meet a price point - and sell more springs.

Ditto. I will relate this to valve springs on a race motor. Springs fail because of heat, (lack of lubrication) tension and cycles. Comparing a spring on a .22 to a piston spring on a LWRC is comparing NASCAR motor spring to a Focus. Different applications.

[BPowderkeg]

Do those springs have to operate at elevated temperatures over a very hot barrel and deal with the same level of compressive fatigue that your piston spring does?

the heat was not a consideration in the original content, sir, you made a general statement, now you are getting into specifics and changing the intent.

ALL springs have a finite life and will eventually fail due to fatigue on a molecular/metallurgical level.

i gotta disagree once more, leave out the "heat" consideration, i have handled guns over 200 y.o. and their springs are as good as the day they were made, in the late 1960's and 70's i personally made over 50 muzzleloader rifles with springs i made myself, my personal muzzleloader is a full stock Hawken flint lock which has two springs in it i had to make myself, after 40+ years that gun is still a functioning perfectly.

YES !! springs do fail but in a gun that is only two or three years old i do not buy into this failure due to heat or any other outside conditions. in the LWRCI guns the spring is well behind the hot exhausting gas.

more later folks it is getting late and i need another cup of "Joe"

[Crow Hunter]

the heat was not a consideration in the original content, sir, you made a general statement, now you are getting into specifics and changing the intent.

Not sure I understand what you are trying to say here.

Heat affects the wear rate of springs. The piston return spring is on top of the barrel isn't it? Heat from the barrel/piston system will reduce the life of the spring. The hotter you get it the faster it will fail.

i have handled guns over 200 y.o. and their springs are as good as the day they were made, in the late 1960's and 70's i personally made over 50 muzzleloader rifles with springs i made myself, my personal muzzleloader is a full stock Hawken flint lock which has two springs in it i had to make myself, after 40+ years that gun is still a functioning perfectly.

Age has nothing at all to do with the performance of a spring (Assuming no hostile environment). The conditions in which it is used and the number of cycles is what causes springs to fail. A 200 year old spring that has 500 cycles on it will be in much better shape than the same spring that is 10 days old that has 50,000 cycles on it. Comparing the springs in a muzzle loader to those in an AR rifle isn't really apples to apples. It really is physics. Do a google search on spring failure modes.

As to discounting heat. Is the spring not mounted on top of the barrel? Is the spring not touching the piston that is in contact with the combustion gasses?

Again, this doesn't mean the LWRC spring isn't defective and that there couldn't be a better design. However, almost identical springs have almost identical lifespans and preventative maintenance requirements.

But you can believe whatever you want. Doesn't hurt my feelings at all.

Maybe you should make a spring to put into your LWRC. You seem to be very good at it and have alot of knowledge about springs.

[BPowderkeg]

As to discounting heat. Is the spring not mounted on top of the barrel? (YES, it is !) Is the spring not touching the piston that is in contact with the combustion gasses? (NO, it is not, there is an exhaust gas "cup"apprx. 2" long, an "op-rod" apprx. 2 1/4" long, a spring retention cup apprx. 5/8" long, the spring 2'' long and lastly a spring retention/return "cup" that is machined to fit in the grooves of the barrel nut, the spring is almost directly over the chamber, there is 1/4'' clearance between barrel and spring, plenty of cooling air for the spring, in fact i could fire a 30 rnd. mag as fast as my little trigger finger could move, remove the hand guard ASAP and hold the spring with my bare hand and not get burned !!)


But you can believe whatever you want. (i certainly will as i believe my experience with LWRCI guns is far beyond yours ) Doesn't hurt my feelings at all. (now that is great, good attitude my friend. )

Maybe you should make a spring to put into your LWRC. (ya know, i have given that some serious thought, if i can find good spring grade wire round stock i will give it a try) You seem to be very good at it (YES sir, i am) and have alot of knowledge about springs. (most definitely, i have made round wire springs the old fashioned way by winding the wire around a mandrel then heat treating it the old fashioned way.)

you may find this helpfull:
http://www.LWRCI.com/t-technology.aspx

scroll down to the firing sequence and note where the spring is located, thank you sir for your feedback and mild demeanor.

[Crow Hunter]

When you are designing it. Keep in mind what it is for.

A buffer spring isn't the same as a trigger/hammer spring. If you get too much of a spring rate on a hammer spring/trigger spring on a muzzleloader you just have trouble pulling the trigger or thumbing back the hammer.

The buffer spring if given too great a spring rate relative to it's free length could potentially interfere with your cycling, especially on lower powered rounds. It could absorb too much of the kinetic energy of your op rod and give you a short stroke.

Have fun!

[johnwilliamson062]

I thought LWRC was supposed to be some extremely rugged piston design?

...well, the gun did continue to function.

[BPowderkeg]

i got my two new springs Wednesday, inspected them thoroughly even with my 50X coin magnifier, these are much better in surface appearance, my home made spring compression gauge shows them to be about 15-20 lbs stronger, in my OPINION these new springs appear to be far superior than the original springs, i installed them Thursday was going to go shooting today but it is too cold, windy and raining.., yaa, i am a wuss when the weather is like it is today.

Crow Hunter said:
"A buffer spring..."..., where did this jump out from ??

"Have fun!" i most certainly will, thank you sir, i just wish you had commented on my description of the parts, size and location.., did you click on the URL ?

johnwilliamson062 said:
"...well, the gun did continue to function."

exactly !! that is why i believe the spring broke on the previous shooting session, BUT ! the spring that had broken in 5 pieces must have had at least 2 separate shooting sessions. in my original post i should have said "pieces" rather than "places".., it really does make a difference.

Of course, you could just donate to the Second Amendment Foundation

i most heartily concur !! SAF is, in my OPINION a much better place to donate towards !!

[Crow Hunter]

Crow Hunter said:
"A buffer spring..."..., where did this jump out from ??

The function of the spring. It acts as a buffer/shock absorber. It prevents oprod bounce and makes sure that it isn't left hanging out for the strike plate on the BCG to hit on the way back closed. The HK 416 has a similar system.

"Have fun!" i most certainly will, thank you sir, i just wish you had commented on my description of the parts, size and location.., did you click on the URL ?

I did, but I can't get to them, I am at work. I can't get through our internet filter (Weapons). I don't own a LWRC, I have only messed with a REPR one time and I didn't get to take it apart.

You own the rifle, I defer to your knowledge on where the springs are. If the spring is in a location where thermal cycling isn't an issue and/or there is a thermal break between the spring and the heat source, you are correct, that particular spring will not be affected by heat. That is why I asked in my responses above about the location of the spring. I made an assumption about the postion of the spring when I made my comment about heat. I was mistaken if it is above the chamber. I thought it was further forward, towards the tappet/gas block.

Do you think the springs are stronger from design or because they have been subjected to less fatigue than the springs in your current rifle? Is the crossection of the spring still the same? Does it have the same number of coils? The same free length? Free length can be a good indication of the fatigue wear on a spring. How did you measure the compressive force on the broken springs?

Let us know how it works.

[BPowderkeg]

The function of the spring. It acts as a buffer/shock absorber.

no kidding ? really ? i had no idea, you really are smart.., WOW !!

Sir..., i know what the buffer spring is and exactly what it is and why it is needed, i just wanted to know why you are bringing it up in the context of an op-rod spring discussion.

I made an assumption...

aaaah ! you should never, never make assumptions, you know what that can lead to.

Do you think the springs are stronger from design or because they have been subjected to less fatigue than the springs in your current rifle? (yes/no !! the springs may be stronger, but.., it is not a mater of stronger ) Is the crossection of the spring still the same? (no, the new spring is.004" thicker) Does it have the same number of coils? (no, there is two more) The same free length? (no, the new spring is longer by two coils) Free length can be a good indication of the fatigue wear on a spring. (true !) How did you measure the compressive force on the broken springs? (i didn't, i measured the compression of the new springs with a crudely self made compression device that i made many years ago when i was into "Hot Rods" to measure the valve spring compression force)

i do hope you are not trying to play a "gotcha" game here, i consider myself an amateur gun smith, took a few corespondent courses, but no formal schooling, i have been repairing guns for nearly 50 years, by trade i was a jet engine mechanic in the U.S. Navy for nearly 30 years, what is your line of work ? are you a metallurgist ?

Let us know how it works.

how what works ?

[Crow Hunter]

i do hope you are not trying to play a "gotcha" game here, i consider myself an amateur gun smith, took a few corespondent courses, but no formal schooling, i have been repairing guns for nearly 50 years, by trade i was a jet engine mechanic in the U.S. Navy for nearly 30 years, what is your line of work ? are you a metallurgist ?

I am a Mechanical Engineer by trade BSME 1997. I have 10 years experience in Automotive Manufacturing (Brake rotors/Hubs) and the last 4 years I have been doing design work (including specing out springs). I also am a Certified Glock Armorer. I grew up in a gun shop and have been playing with guns for about 30 years.

I was genuinely trying to help you and others who might be reading this post and be in a similar situation. Sometimes reading something like this can cause people without your experience with guns to panic unnecessarily (note post by Walt below on LWRC forums). Not trying to play gotcha at all.

I did some research and depending on the born on date of your rifles you may have bad springs. At some point in time LWRC's spring vendor made a bad batch of springs. Those springs were not produced to the correct specifications. LWRC was supposed to have contacted all the owners and sent them replacement springs of the correct design. Several of the owners on LWRCforum have similar experiences to yours and change out their springs at 5,000 round intervals. You are specifically mentioned.

http://forum.lwrci.com/viewtopic.php...667ee009fad16d

You made some statements that I believed to be incorrect about springs that I was trying to share information with you. After you said you got in new springs and they were stronger, I was interested to know how you knew they were stronger. I don't know how to measure a broken spring for strength and that might be a useful thing to know. I was thinking that maybe you measured the compressive force on a small section and extrapolated that to the free length. I was going to let you know that you can't do that because the spring force on a spring changes based on the number of coils and you have to model it as a fully compressed cylinder to get a good approximation. Hooke's Law there is a good explanation on Wikipedia. I asked about the other dimensions on the spring to see what might have changed. A very good friend of my brother owns a gunshop locally that is the largest LWRC dealer in the US. This info might get me even better discounts and to shoot even more machine guns.

It truly doesn't hurt my feelings if you don't believe me or if you try to make me look like I don't know what I am talking about. I don't get any pleasure for making people look dumb. I do however enjoy helping people and I have had my share of frustrations with guns (Bushmasters in particular) and I was trying to help you out.

Let us know how the new springs work out when you replace them shoot the guns. Any difference in cycling of the gun? Anything else different from when you shot it before changing the springs.

ETA: Hooks Law and fixed the explanation that I mangled.

[BPowderkeg]

Crow Hunter, first of all i want to thank you for posting that URL, i read the entire 4 pages entertaining and amusing to say the least.

congratulations for being a Mechanical Engineer, i was always interested in the Mechanics of things, getting my hands in there, tearing it apart, see how it works and put it all back together and making it function better than before, i have over 50 years gun and automobile engine experience, almost 30 years jet engine repair,overhaul and test experience.

I was genuinely trying to help you and others...

thank you.., i see that now after reading the URL to LWRCI

You are specifically mentioned.

WOW !! i am famous and honored i would be mentioned on that world renowned highly prestigious site

I was interested to know how you knew they were stronger. I don't know how to measure a broken spring for strength and that might be a useful thing to know.

i guess i should have mentioned, i measured the new springs against an original unbroken spring from another rifle.

...a good explanation on Wikipedia.

oooh, come now .., wikiliarpedia ???? half that crap written there is by people who think they know it all !!

on the last of the 4 pages of entertainment and amusement, Mr. Wolfe said something that proves to me he knows nothing about "how a damn AR works" at least how an LWRCI piston "AR" works, i am glad he admitted to NOT being an engineer, read below,

Mr.Wolfe says: Therefore, the spring does nothing but return the piston cup with less force than the BCG would.(i say BS !! or FALSE, the spring limits the travel of the piston cup and op-rod rearward, therefore the self-regulating short-stroke gas-piston system due to the spring being located over the chamber) I'm not an engineer, so I don't know how much of a difference that makes, but I understand how a damn AR works.

i just wanted to correct Mr. Know-It-All.., those are the guys who write on Liarpedia

oooooH ! you can Quote me on that to him.

[Crow Hunter]

thank you.., i see that now after reading the URL to LWRCI

I am not a member over there, just googled the oprod spring and directed me there. I thought it was interesting that your specific thread was mentioned.

i guess i should have mentioned, i measured the new springs against an original unbroken spring from another rifle.

Ah, that makes more sense. I was wondering if you had a way. Hands on experience usually trumps theoretical experience and sometimes people develop some pretty ingenious methods of measuring things with alot of experience. I thought I might be able to steal an idea from you.

oooh, come now .., wikiliarpedia ???? half that crap written there is by people who think they know it all !!

Their Hooke's Law explanation and equation is correct. Which is what I was referring to. I checked it against my mechanical engineering handbook. (Which is a great resource by the way) Wikipedia is usually correct on it's math stuff. It is hard to lie about that.

The information that Darren posted over on the LWRC forums was the most informative (He is a LWRC employee after all). He mentioned a design change that put in a newer spring (which you seem to have) and a spring stop (I think that was what he said, I can't get to it at work). I assume that is something to limit the spring extension travel. That might have been contributing to early spring failure by hyper extending the spring, especially if there is nothing that keeps the spring from over extending.

So did you change it out and try it yet? It would be interesting to see if there is any difference, especially since you have an old design and new design spring.

After I got to thinking about it, I actually think a weaker spring (that returned less of the kinetic energy) would be worse than a stronger spring (that returned more).

Either way, I am interested in the results.

As an aside, at the last LWRC Days at my LGS they had several of the M6's there with happy switches. They were running full mags through them and then sticking the front ends into 5 gal buckets to cool the gas blocks down. My brother said there was alot of steam coming back out through the ejection ports.