ATTENTION: LWRCI Piston Gun Owners

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.
 
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 ?
 
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. :D

http://forum.lwrci.com/viewtopic.php?f=2&t=10979&sid=9902ae66fe326790b9667ee009fad16d

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.:eek:
 
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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 :D ;)

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.
 
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.:D

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. :D
 
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.

yes, the spring has been installed and will be shooting both carbines with new springs, but i doubt if i'll be able to notice any difference as the one gun has a two stage trigger and an Enidine hydraulic buffer plus it is almost two pounds heavier.
 
C.H., i replaced the spring and the rifle functions perfectly..., BUT !! to me that is irrelevant, here's the gig, http://www.lwrci.com/t-warranty.aspx
LWRCI™ products are warranted to be free from defective materials and workmanship for life of the original purchaser. LWRCI™ obligation under this warranty shall be limited to (1) repairing or (2) replacing any product upon inspection at LWRCI™ and based on its discretion, is found to defective in material or in workmanship.

in my OPINION that spring falls within the "defective materials" in the warranty, then they say the spring should be replaced every 3,000 rounds fired and we have to BUY a new spring.., BULLSKEET !! that spring should be covered under the warranty and at NO charge to the owner of the rifle.

there is no other "gun maker" who warrants their product for life then tells you, you have to buy parts that are broken or worn out due to "defective materials", AND..., that spring when needed to be replaced at regular intervals is "DEFECTIVE", IF.., say for instance the bolt and barrel extension lugs wore out after 5,000 rounds we have to buy a new barrel and bolt ????? once more.., BULLSKEET

i agree some parts on any gun do wear out and need to be replaced, but only after 3,000 rounds ?? gimme a farking break !! there is NOTHING in the manual i got with the gun that says certain parts in the gun will break/fail after 3,000 rounds and must be replaced and purchased by the owner, i would think that a "life time warranty" means just exactly that !

IF there are any..., and i am certain there are some LWRCI lurkers here, please try to explain why your "life time warranty" isn't worth a shiite when we have to buy on a regular basis your crappy springs to keep the gun functioning and operable !! :eek: :eek:
 
I see what you are saying and will think about it, but my initial reaction is, "Actually quite a few varmint chamberings wear out the barrel in 3,000 rounds and no company pays for new barrels." Just an initial reaction though.
 
I see what you are saying and will think about it, but my initial reaction is, "Actually quite a few varmint chamberings wear out the barrel in 3,000 rounds and no company pays for new barrels." Just an initial reaction though.

yes sir, i fully understand, much to my chagrin, i sold a Sako Vixen .222 Rem. L-46 action many years ago because i shot out the barrel in close to 7,000 rnds., but Sako claimed no "life time warranty"

here is another point i would like to make about springs, how many springs will you find in any AR-15/M4 lower ? how many of them do the various Mfgrs. of these guns recommend them to be changed at regular intervals ? NONE !!

BTW AR-15's have 8 springs in them,

1. Bolt Catch Spring

2. Buffer Detent Spring

3. Disconnector Spring

4. Hammer Spring

5. Magazine Catch Spring

6. Safety Detent Spring

7. Take Down Pin Spring

8. Trigger Spring
 
please sir, let's stay on topic.., which is SPRINGS !! OK ?

how many springs in an AR-15/M4 do the various Mfgrs. of these guns recommend them to be changed at regular intervals ?

this is the question that needs answering, so if you would, please stay with me on the spring issue.

when buying ANY gun with a lifetime warranty, what do you expect from their "lifetime warranty" ?? for me it means every, and i mean EVERY part of that gun is warranted right down to the very smallest part which is that tiny "C" clip on the end of rod of the dust cover !!
 
The issue here is what you expect from a warranty.
I am not sure what most manufacturers suggest for ARs, but I know most people that own ARs and shoot them a lot have spare springs, extractors, etc.

It's like expecting your cars warranty to include tires and oil changes.
 
how many springs in an AR-15/M4 do the various Mfgrs. of these guns recommend them to be changed at regular intervals ?

The springs that you listed aren't very high wear items and can more easily be "over engineered" without affecting function.

Here is a recommended PMS interval for the M4:

2,500 round interval,
Inspect and replace as necessary extractor spring, insert and O-ring

5,000 round interval
Replace extractor spring
Replace extractor insert
Replace extractor
Replace Crane O-ring
Replace gas rings
Replace action spring

10,000 round interval
Replace bolt
Replace lower receiver parts - (I assume this would include the springs since the they aren't specifically excluded)

15,000 round interval
Replace barrel

Of course, YMMV. :D

I don't know that I have ever seen this info in a manual. I think this info is normally directed to armorers for preventative maintenance. You can go longer than what is posted above, but you will have to know what to look for when something is bad/getting ready to fail.

In manufacturing when setting up PM schedules on equipment, we try to shoot for 85% of the expected usable life of the component for some "safety factor" for variability in manufacturing the component. I am sure you are even more familiar with this than I am based on your previous work experience.

when buying ANY gun with a lifetime warranty, what do you expect from their "lifetime warranty" ?? for me it means every, and i mean EVERY part of that gun is warranted right down to the very smallest part which is that tiny "C" clip on the end of rod of the dust cover !!

To me, a lifetime warranty means that if it fails due to a defect either in construction or assembly, it is a warranty issue. A defect meaning something is not manufactured to the specification. In the case of springs, wrong material, bad heat treat, wrong ID/OD something like that.

If the expected life of a component is X number of rounds and it fails at that point or later, it isn't a warranty issue. If it fails earlier for a defineable defect, it is a warranty issue.

This specifically would not include a wear item that failed due to use.

Now if it is a "guarantee", that is a different story.
 
The issue here is what you expect from a warranty.
RIGHT ON !! i have an old Colt AR-15 SP-1 made in 1974ad, i have no idea how many rounds have been fired thru it, but i would guess it is over 10,000.., NOT one part in that rifle has ever been replaced due to wear, breakage or any other malfunction.
If the expected life of a component is X number of rounds and it fails at that point or later, it isn't a warranty issue. If it fails earlier for a defineable defect, it is a warranty issue.
agreed.., BUT ! i believe the company (any company) should have an unconditional ONE YEAR warranty, rather than a "life time" warranty which in my OPINION is worthless if they will not replace broken parts during the "life time" of the owner or rifle.

i guess i expect too much from a "life time" warranty, so i suppose i need to buy two identical rifles, one for shooting and one for parts :eek:

i believe this topic has run it's course and this is all i got to say, unless someone has a reply that needs addressing. :D
 
an unconditional ONE YEAR warranty
Newegg.com used to do this. I had a buddy who just so happened to drop his lap top around day 360. Unconditional warranties are pretty easy to take advantage of, heck in some states and warranty at all is pretty hard for the company if the consumer pursues things. Why Ruger does it the way they do.
 
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