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VeeDubbinJetta91
08-12-14, 13:32
Hey all, I hope this is in the correct section, I was at the range this past Sunday with a friend who brought along his newer sig 556, about 49 rounds in he found the bolt wouldn't close. Upon further inspection we found this little piece of metal stuck in the barrel extension
http://img.tapatalk.com/d/14/08/13/7y8ahavu.jpg

We took the gun out to ask the range staff and they were not sure where it came from, upon further inspection we found where it's home was
http://img.tapatalk.com/d/14/08/13/ynyjupum.jpg

We also found it chewed up a lug on his bolt as well
http://img.tapatalk.com/d/14/08/13/udy2aby3.jpg

He contacted sig today and they said either toss the part and they will send him a new bolt or ship the gun to them, they will reinstall the piece and replace the bolt. He is not very satisfied with these answers so he asked I post here. What are your guys/gals opinions on the matter? The gun has less than 1000 rounds total through it and it seems like a pretty decent failure. He appreciates all your advice and info

Thanks
VeeDubbinJetta91
08-12-14, 14:24
Sorry Sig 516 not 556
devildogljb
08-12-14, 14:24
If i was him get it fixed and sell it. Get a colt or one of the other great companies making rifles. Sig needs to start stepping up their quality control. But this is just my opinion.
Sasahara
08-12-14, 16:48
What exactly is the purpose of this piece?
VeeDubbinJetta91
08-12-14, 16:53
According to what sig told him, it was a support for the extractor when the bolt is closed, otherwise I have no idea
Digital_Damage
08-12-14, 17:07
Send it in, get it fixed and they sell that thing. I for one have never seen anything like that.
Heavy Metal
08-12-14, 17:28
If it is like the H&K 416, it is to ensure the extractor stays closed while inside the barrel extension.
Digital_Damage
08-12-14, 18:02
If it is like the H&K 416, it is to ensure the extractor stays closed while inside the barrel extension.

That would be seriously ironic, a part that is designed to be a reliability upgrade causing reliability issues.
Sasahara
08-12-14, 23:06
According to what sig told him, it was a support for the extractor when the bolt is closed, otherwise I have no idea

Thanks for the reply. First time I have ever seen/heard of such a thing. Also did not know the 416 had this feature. We do not get many cool toys around me in this state so have not had a chance to inspect a genuine 416 upper or even the MR556.
BTL BRN
08-13-14, 11:32
Another vote for get factory fixed and sell.
BufordTJustice
08-13-14, 12:30
Another vote for get factory fixed and sell.
And another.
sinlessorrow
08-13-14, 12:32
That would be seriously ironic, a part that is designed to be a reliability upgrade causing reliability issues.

The idea behind a extractor support is to keep the weakest link of the bolt from going in case of a obstructed bore or overcharged round.

Ideally it will keep the upper from detonating, but it is one more piece than can....and does fail occasionally.
VeeDubbinJetta91
08-14-14, 17:22
He's gonna ship the gun back to sig to get fixed it sounds like, however he's on the fence about getting rid of it, he really wants a piston gun
richiecotite
08-14-14, 18:33
Colts is $799. Ain't no reason to deal with that bull...
Clint
08-14-14, 18:37
Good idea, bad execution.


The idea behind a extractor support is to keep the weakest link of the bolt from going in case of a obstructed bore or overcharged round.

Ideally it will keep the upper from detonating, but it is one more piece than can....and does fail occasionally.
texasgunhand
08-15-14, 02:43
There was a Sig m-400 that had the same problem,the post is here some were.The guy shipped it off and they replaced the whole upper and had it back to him in like 7 days i think.

Only the 2nd one ive seen fail so far...The one thing i would do is to put the gun back to STOCK if you have added a bunch of upgrades,becouse they are, like i said, gona change the barrel out or the whole upper...It is what they have said it is, it supports the extractor if there is an over pressure.

Would you please post if the piece looks like it is pinned in or pressed in or if its tack welded etc???
Send it back they will fix it free of charge..let us know how it goes.
.46caliber
08-15-14, 07:04
There was a Sig m-400 that had the same problem,the post is here some were.The guy shipped it off and they replaced the whole upper and had it back to him in like 7 days i think.

Here is said thread:

https://www.m4carbine.net/showthread.php?t=122488


Sent from my Nexus 4 using Tapatalk
Digital_Damage
08-15-14, 07:25
He's gonna ship the gun back to sig to get fixed it sounds like, however he's on the fence about getting rid of it, he really wants a piston gun

Don't know why he would want that but thel him to get a LWRC then
Ned Christiansen
08-15-14, 08:55
Woulda been totally fine to toss the support and run it as pictured, without it, for the life of the gun.

But yeah, it shouldn't be falling out. The real factory repair would require them taking the barrel out (and no doubt just putting in a new barrel).

Too bad it didn't happen with more rounds on the barrel, which woulda meant more "free barrel life" from SIG.

I won't say it's a solution to a non-existent problem, but the necessity factor was low to start with and given how they apparently did it, that has now gone negative. Never had one apart but I had assumed that little fekker was installed from the outside of the barrel extension and had a head on it like an extractor spring buffer which would keep if from ever falling through. They went to what I would way was a lot more manufacturing trouble by making a spotface for it on the inside (that wasn't easy) and apparently it installs from the inside and is peened over on the outside to keep it from falling back in.
justin_247
08-16-14, 15:21
This is retarded.

So, obviously Sig thinks their piston design causes some kind of problem that requires them to add this additional piece. And now the piece falls out, causing malfunctions. Ingenious.

I thought pistons were supposed to solve all these DI reliability issues! /s

Anyways, your friend needs to get rid of that gun ASAP and get a good DI gun. Colts are going for between $800 - $950, so there really is no excuse.
.46caliber
08-16-14, 15:50
This is retarded.

So, obviously Sig thinks their piston design causes some kind of problem that requires them to add this additional piece. And now the piece falls out, causing malfunctions. Ingenious.

I thought pistons were supposed to solve all these DI reliability issues! /s

Anyways, your friend needs to get rid of that gun ASAP and get a good DI gun. Colts are going for between $800 - $950, so there really is no excuse.

Sig uses this item on their DI and piston guns. It has nothing to do with their piston system. Its purpose is to support the extractor. See Ned's post for more.

Sent from my Nexus 4 using Tapatalk
justin_247
08-16-14, 17:30
Sig uses this item on their DI and piston guns. It has nothing to do with their piston system. Its purpose is to support the extractor. See Ned's post for more.

Probably due to some production streamlining processes. Or maybe they thought the DI guns could use it, too.

It's an interesting concept and a few different companies do it.

AFAIC, something like that should not be added to the system unless it is actually somehow machined into the extension. It's an unnecessary failure point.
RMiller
08-16-14, 18:06
Another vote for factory repair. Then buy a BCM or Colt.
VeeDubbinJetta91
08-16-14, 21:01
Agreed, I took him out today with my new bcm rifle I just built and he really enjoyed it, he was talking with a few of the guys at the range today and they told him to sell it too. I guess I'll see what he ends up doing
mtdawg169
08-22-14, 13:01
Send it in, get it fixed and they sell that thing. I for one have never seen anything like that.

I've actually seen 2 or 3 reports of the same exact failure on these Sigs. Crazy.
Heavy Metal
08-22-14, 18:38
I've actually seen 2 or 3 reports of the same exact failure on these Sigs. Crazy.


Sounds like a bad batch.
.46caliber
08-22-14, 18:42
Sounds like a bad batch.

I've seen this failure twice reported on M4C. I too wonder about a batch issue, but there was a decent time span between the two reports here. I wonder if there's more on M4C that I haven't found.

The other was on an M400 DI rifle.

OP, any update as far as his things went with Sig. Assuming he sent it in.

Sent from my Nexus 4 using Tapatalk
VeeDubbinJetta91
08-22-14, 23:25
He opted not to send it in and just have Sig send him a new bolt, he decided to just run it without having it reinstalled, I told him he should have have them fix it properly as he didn't spend that much on a rifle to have it fail so quickly, but he did not.
RMiller
08-23-14, 00:16
He opted not to send it in and just have Sig send him a new bolt, he decided to just run it without having it reinstalled, I told him he should have have them fix it properly as he didn't spend that much on a rifle to have it fail so quickly, but he did not.

To each their own.