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I have a HK MR556 Upper that I am using on a KDW Lower with a Sliding MAGPUL Stock. The new upper came with a HK TUNGSTEN Buffer and Buffer spring. I switched out my M4 Carbine buffer and spring and installed the HK Buffer and spring. My question is can I use a M16A2 Standard Stock buffer spring spring as a Back-up spare? They look about the same length/ The HK Buffer spring and the A2 Buffer spring. My M4 Spring is shorter than the HK Spring and the HK Manual says to use their Spring only, but they are $60.00 plus dollars and the A2 Springs are Like $5.00 TO $10.00 DOLLARS. I am getting a Spare parts Box together for the HK UPPER, I have a lot of M4 Spare parts for my other Rifle. So will the Other A2 Spring work? Thanks:wink:
 

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I'm sure there is some configuration that might work temporarily (I'm not sure what that might be), but obviously it won't be as optimal as the factory parts.
 

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As it says on page 28 of the MR556 Operators Manual, Reassembly Section 1c:

WARNING: Ensure that only the proprietary HK buffer (marked with the HK logo and
red dot) and recoil spring (action spring), also marked with red paint, are installed
in the MR556A1. Use of non HK buffers and recoil springs could result in cycling
problems and affect the reliability of the MR556A1 (Fig. 38).
So I'm guessing no.
 

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The HK spring has much greater tension as the piston operation of the HK416/MR556 produces more rearward energy.
 

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Has anyone heard of a newer or updated HK buffer spring in the last year. I ordered 2 from Center Mass Firearms and they are a inch longer and look a little different than my 416 spring and my MR556 spring. The Center Mass springs also look different than the pics on HKparts.net website.

I emailed Center Mass and they replied that there is a newer version 416 buffer spring out and that is what I have.

Here are some pics of the buffer springs in question:



 

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Do not mix carbine and rifle action springs.

If you want a replacement carbine spring that's in the same power range as the HK action spring, that is high quality and less in cost, get a Wolff XP carbine spring SKU: 16501 at the following link: Springs for COLT AR-15, CAR-15, M-16, M4, 9mm SMG AND SPORTER Rifles & Shotguns.

For what it's worth, I decided to go with the Vltor A5 system and found that I still needed an XP rifle spring. If the rifle settles down within a few hundred rounds as others have stated theirs have and the ejection gets weaker, I can go back to the standard A5 spring (also the standard rifle spring) and keep my ejection ideal.
 

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HK is constantly making changes to parts. Many changes are simply a change in OEM vendor. The two different springs may have merit, but my guess is that it's simple a different OEM manufacturer. All the HK416 springs I have seen have the red paint (or reminants of), which is merely an indentification feature.
 

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A little help

Has anyone heard of a newer or updated HK buffer spring in the last year. I ordered 2 from Center Mass Firearms and they are a inch longer and look a little different than my 416 spring and my MR556 spring. The Center Mass springs also look different than the pics on HKparts.net website.

I emailed Center Mass and they replied that there is a newer version 416 buffer spring out and that is what I have.

Here are some pics of the buffer springs in question:



Bermise,

Having handled hundreds of factory HK 416/MR556 upper kits and HK buffer springs through the years. The spring should be marked with red paint or like Chopstix mentioned remnants of the paint in some cases. I have on occasion, handled heavily used HK416 springs where all of the paint was worn off. Even still, it would be obvious that these were heavily used and not new springs to begin with. Another identifying feature that is a dead giveaway on the HK416/MR556 buffer spring is the fact that HK "grinds" the each end of this particular spring. They should have grounded ends on both contact ends of the buffer spring. Now I will mention this has not always been the case but is something to look for and is almost always done but I have seen exceptions to both of these indicators as well. Can you post a picture of the contact ends of the springs? This may be another way to help identify what you have.

In HK armorer's school we were told that if you did not use the factory HK tungsten filled buffer and heavier HK spring that there would be a higher probability of under performance of the upper while in use. With that said the HK 416 and MR556 series should ONLY be used with the factory correct buffer and spring to retain the utmost reliability. I hope this helps.
 

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Bermise,

Having handled hundreds of factory HK 416/MR556 upper kits and HK buffer springs through the years. The spring should be marked with red paint or like Chopstix mentioned remnants of the paint in some cases. I have on occasion, handled heavily used HK416 springs where all of the paint was worn off. Even still, it would be obvious that these were heavily used and not new springs to begin with. Another identifying feature that is a dead giveaway on the HK416/MR556 buffer spring is the fact that HK "grinds" the each end of this particular spring. They should have grounded ends on both contact ends of the buffer spring. Now I will mention this has not always been the case but is something to look for and is almost always done but I have seen exceptions to both of these indicators as well. Can you post a picture of the contact ends of the springs? This may be another way to help identify what you have.

In HK armorer's school we were told that if you did not use the factory HK tungsten filled buffer and heavier HK spring that there would be a higher probability of under performance of the upper while in use. With that said the HK 416 and MR556 series should ONLY be used with the factory correct buffer and spring to retain the utmost reliability. I hope this helps.
Thanks for the explanation. I will take some close up pics of the spring ends and post tomorrow some time. I want to be sure I have the right springs.
 

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Hard to tell from the pics but the ends do not look to be "ground" looks more like it was cut or chopped. I also got these for $30 each which is a fairly good deal for new 416 springs. Maybe too good of a deal....
 

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Dude, those look like standard AR15 rifle stock springs........

Measure the springs "free length". If the spring is between 13 1/2 and 11 3/4 inches, they're rifle springs. If they're between 11 1/4 and 10 1/16 inches, they're carbine springs.

The lower numbers given are the bottom line acceptable by Mil standards for spring length before rejection and replacement though, so no new springs should be anywhere close to the lower numbers (either 11 and three quarters inch for rifle springs or 10 and one sixteenth inches for carbine springs).

Looking at your pictures, either your HK spring is really worn and is out of spec, or those are the longer rifle springs.

If they are the longer rifle springs, DO NOT USE THEM in a carbine receiver extension (buffer tube to most people).

And for 30 bucks, you got jacked. Even high quality Wolff springs don't cost that much.

Sorry bud.... :-(
 

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That is interesting tlrgsxr, apparently there are a few versions of the 416 spring. My new MR556 spring looks slightly different than my used 416 spring, but they are the same length.

I guess I could try to call the customer service dept at HK HQ in the states and see if I could mail them a spring to verify. But I have heard that there CS can suck if your not a big dealer or LE.

In the mean time I will buy a buffer spring from HKparts.net. A little more expensive but at least I know for sure what I am getting.
 

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Try centermassfirearms.com. Hk parts at more reasonable prices.
Ha! That is who sold me these knock off buffer springs in question here.

I compared them tonight to a rifle length buffer spring and bingo! Identical in length and coil spacing. I am going to contact Center Mass Monday.
 

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Ha! That is who sold me these knock off buffer springs in question here.

I compared them tonight to a rifle length buffer spring and bingo! Identical in length and coil spacing. I am going to contact Center Mass Monday for a return and refund.
Silly question, but have you ACTUALLY TRIED these buffer springs before making these allegations? Have you voiced these concerns to Lee/Centermass directly? If not it seems unfair to throw them under the bus at this point.
 

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I have purchased from Centermass in the past and have always had extremely good luck with their parts and their customer service is great. There prices are fair also for what I have bought.
 
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