Check your 556 for wear/damage to the carrier

[SigOhio]

So far, 35 members on here have discovered that the carrier in their newer build 556 rifle is hitting the receiver causing damage to the carrier. Please check to see if your rifle has the same issues so we can try to identify a problem batch.

This interference may be causing accuracy issues since it causes the carrier to bind just before coming all the way forward. But more importantly is that there is a defect causing damage that could compromise the longevity of a critical part that sees high stresses. I personally would like my 556 rifle to last me a long time, and I'm sure others here would as well.

Serial numbers with known carrier-to-receiver interference:

JS0228XX: Aaron (200 rounds) [mild]
JS023XXX: cufan99 (15 rounds) [mild]
JS0235XX: abrams_34 (800 rounds) [mild]
JS024XXX: dd0s (200 rounds) [moderate]
JS025XXX: bluecollarkid (300 rounds) [mild]
JS0250XX: fun2shoot (800-1000 rounds) [severe]
JS02500X: cheney (800 rounds) [moderate]
JS0255XX: jjksutton (120 rounds) [mild]
JS0259XX: tibim (800 rounds) [moderate]
JS0261XX: 762nato (50 rounds) [moderate]
JS0261XX: paxbnm (90 rounds) [mild]
JS0266XX: Parsley Charlie (200+ rounds) [mild]
JS0267XX: TwiztidKlownzTX (200 rounds) [mild]
JS027XXX: SigOhio (750-800 rounds) [severe]
JS0272XX: aaks38 (350 rounds) [severe]
JS0273XX: KB (cycled manually) [mild]
JS0277XX: 2Loud4You (200+ rounds) [mild]
JS028XXX: rioaguanegra (190 rounds) [mild]
JS028XXX: kylerudibaugh [mild]
JS0286XX: tangodown (hand cycled) [mild]
JS02963X: Mastoo (100 rounds) [moderate]
JS0300XX: Draco556 (1200 rounds) [mild]
JS0307XX: coffey (500 rounds) [Mild]
JS0309XX: hattaresguy (450 rounds) [mild]
JS0313XX: Sapper326 (360 rounds) [moderate]
JS0319XX: San Francisco SIG guy (600 rounds) [minor]
JS0320XX: TexRN (700 rounds) [Moderate]
JS032XXX: bravo5two (400 rounds) [moderate]
JS0332XX: anubismp (~700 rounds) [moderate]
JS034XXX: haiedras (125 rounds [mild]
JS0352XX: mlando (300 rounds) [Mild]
JS0378XX: bubbacop (200 rounds) [mild]
JT0004XX: Sam_SIG (200 rounds) [mild]
JT0012XX: bolt carrier (100 rounds) [moderate]
TP001XXX: EvilBlackGun (65 rounds) [mild]


Below is a list of serial numbers with NO wear or marking on their carrier at all, even though some have a quite high round count. Some have also indicated their upper receiver does not have the “hump” shown in the below picture with the red arrow.

JS0028XX: sigshooter
JS0034XX: ullie
JS0061XX: ullie
JS0076XX: Gopher (1000 rounds)
JS0085XX: Ratpick [no hump]
JS00878X: c_morse
JS0090XX: flascot007 (2000+ rounds)
JS0090XX: Nittany Lion [no hump]
JS0094XX: rhWestermeyer (~6500 rounds)
JS0095XX: Nittany Lion [no hump]
JS0095XX: Ratpick [no hump]
JS010XXX: WayaX (300+ rounds) [no hump]
JS013XXX: Ratpick [no hump]
JS0134XX: 762nato (400 rounds)
JS0138XX: jaygun (1000+ rounds)
JS014XXX: Ratpick [no hump]
JS014XXX: shade_1313 (150 rounds)
JS014XXX: greenhornet (1000 rounds)
JS01489X: moses [20 hump]
JS0157XX: ercarr S/N [no hump]
JS017XXX: thevatman (hand cycled)
JS017XXX: bpowell (500 rounds)
JS017XXX: rogue2 (600 rounds)
JS018XXX: 5711usmc (500 rounds) [no hump]
JS0181XX: Longrifle
JS0187XX: krayg (1200 rounds)
JS0188XX: a80ndrn8
JS019XXX: thevatman (6250 rounds) [no hump]
JS0198XX: xtant8420 (700 rounds) [no hump]
JS0225XX: SkyPup
JS0236XX: jpcdmd (500 rounds) [hump]
JS0309XX: Jaco (~200 rounds)
JS036XXX: revarc (500 rounds)
JS037XXX: rioaguanegra (90 rounds)


This collection of serial numbers shows a clear trend for this wear issue with SN ~23,000+ rifles. Earlier builds appear to be problem free. If your rifle has these problems, please add it to this list. Below are the pictures showing the wear damage I am referring to. Mild, moderate, or severe relates to the amount of wear seen.

tibim's:


SigOhio's original damage after ~750 rounds:

Sig gunsmith attempted quick "fix" by grinding off corner of carrier, new damage is partially visible:

Detail of new damage (rolled over leading edge + shiny marks) after only 50 more rounds fired after "fix":

Here is the hump where the carrier hits the upper receiver:

fun2shoot's:

[Longrifle]

You should also post a picture where it grinds against in the upper receiver. I remember seeing it in an earlier thread.
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I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the blanket of the very freedom that I provide and then questions the manner in which I provide it.

Colonel Jessup (Jack Nicholson) in "A Few Good Men"

[SigOhio]

[Longrifle]

I have a similar "hump" in my upper receiver, though not as high and don't have any grind marks. There is definitely machining quality control issue there. Mine is JS 0181XX (July 2008). The 3 SNs you posted are pretty close together, and like you said, may be a batch problem.
_________________
I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the blanket of the very freedom that I provide and then questions the manner in which I provide it.

Colonel Jessup (Jack Nicholson) in "A Few Good Men"

[Sapper326]

My Classic has those same wear marks on both the upper and the bolt carrier. My SN is JS0313XX made 4/22/2009. I really did not even notice it until reading this thread. I will try and get some pics but it looks very similar to the pics up above.

[SigOhio]

Updated the list in the first post. If you have this issue could you also comment to how many rounds you have fired, and how your accuracy is?

[Sapper326]

I have put roughly 360 rounds through the rifle.

[fun2shoot]

JS0250XX I have it as well. About 800-1000 rounds through my Classic.
Any word on Sig about this issue? I do not like the idea of the Sig smiths "quick fix" one bit.
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Glock 20
Sig 556 Classic

[762nato]

I checked my two sigs compared carriers,commando-jso134xx-April 2008,its fine 400rds later,but the classic,JSO261XX-JAN.2009,50rds.fired.I can see where It's also starting to wear right on the corner just like yours.I need to shoot it more to see if it gets worse.But my commando does'nt have the slightest wear in those area's with eight times the ammo fired so far.Maybe your on to something here,My commando carrier is shaped alittle slimmer where they did the grinding on your carrier the radius is a little different,that's really hokey in my opinion how they did the grinding to cut corners .If any of you guys have access to different models,old/new,could you please compare the carriers to see if theres any difference in width/thickness,ect.Thank You,

[Longrifle]

I wonder if this problem is inherent to the new style "classic" lower. None of the older (from last year and older) NATO Stanag style lowers seem to have this issue.
_________________
I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the blanket of the very freedom that I provide and then questions the manner in which I provide it.

Colonel Jessup (Jack Nicholson) in "A Few Good Men"

[762nato]

I'm not sure,It could possibly be the upper's out of spec,and or the carrier,but I seem to think the carrier is the culprit.The classic carrier is just alittle different than the commando carrier,less meat,and a little different radius on the carrier.If someone has the insturments to correctly measure these parts,that would tell us more about the different sizes and radiuses/angles of these carriers.You know the old verus's the new. That's maybe why there catching on the corner like they are.

[tktm]

I have seen similar stuff in other AK's. I would be more concerned if it were damaging the locking lugs, or the piston.

[SigOhio]

I have updated the original post again. Looks like we are up to 6 members with this issue now and we are seeing a trend with the serial numbers. Early builds seem to be problem free. If you have this damage, please also post a pic of your carrier as well. It will help document what we are finding. No word yet from Sig.

Also, please comment on what sort of accuracy you are getting out of the affected rifle.

[Sapper326]

How much different is the 556 upper from the 550/551 upper? I wounder if this is even an issue or not. I have not seen any adverse effects from the wear as I am still able to maintain 1.5" groups at 100 yrds (which is what I would expect from such a weapons platform). This could be normal wear that takes place with this type of a platform. Unfortunately I don't think there is many people who own a real 550/551 and shoot them a lot. If there is someone who has access to one maybe they could check to see if they see the wear.

[SigOhio]

[ullie]

[jjksutton]

I have the same issue...JS0255XX (26 Jan 09)

Only 120 rounds (although I did hand cycle it a few hundred times). I can see a wear mark in the same spot. We'll see if it gets worse. I am going to the range Sunday.

I shot 2" groups at 100 yds with it which is more than good for me. We'll see if it keeps up.

Also, I had some issues with binding for about the first 30 or so rounds then it cleared up. I figured it "fixed" itself once. I don't know if one thing has anything to do with the other though.

[2Loud4You]

JS 0277XX Feb 11 '09 birthdate.

I've hand cycled it probably 500+ times and put at least 200 - 300 rounds through it. It has a VERY faint nick there. I barely even saw it, I'll see how it looks after firing more rounds through it.
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NRA Endowment Member
Sig 556 Holo

[tktm]

[tktm]