Sig 556 SBR 10 inch = junk

[Kip42]

I saw a sig sbr fail to feed. The slide locked back like it was empty and it was not mag related. Mine finally cleared and I had the same problem today at the range, with diff ammo, and my gun was perfectly clean and lubed! It shoots a 5 inch shotgun pattern from a bench at 25 yards! My draco century for 350 bucks shoots better at 50 yards without a stock!


Is the sig under gased? When I threw my suppressor on it there werent any issues. I think the extra gas caused it to work better. I think im done with anything that is not an ak or .308...

Maybe I will sbr a Draco.

[66427vette]

Strange. We have three of them made from the pistols and run 100% with any ammo from blackhills to tula. Did you sbr a pistol or cut down a rifle?

[Ronzo]

Wow, my buddy has an early SIG556 pistol that he form 1ed and it runs like a top. How did it run before you put the stock on?

[ATCDoktor]

Mines a formed 1 pistol as well and runs like a Top. Not my most accurate rifle (2" or so at 100 yards) but its been 100% reliable.

[66427vette]

sounds like a rifles was cut down . gasports/ bad recrown or piston assembly was taken apart and not put back together right.

[Sigproshooter]

I am personally very skeptical of these claims.

Methinks there are many more details that are the reason, not that Sig has trouble getting an over-gassed piston rifle to run as an SBR.

[m3s90]

I have one from the factory, runs like a top.

[rommel2000]

My 16inch barrel Sig 556 with an AAC Ranger2 suppressor was locking open every 2-3 shots with Fed 55 grain factory ammo. I've used this suppressor and ammo combination on 10.5 and 16inch AR's with no problems.The last time I shot the Sig I used my own handloads with reduced powder charges and it ran perfect. I assume the gun is overgassed with the can on it.

[Sigproshooter]

My 16inch barrel Sig 556 with an AAC Ranger2 suppressor was locking open every 2-3 shots with Fed 55 grain factory ammo. I've used this suppressor and ammo combination on 10.5 and 16inch AR's with no problems.The last time I shot the Sig I used my own handloads with reduced powder charges and it ran perfect. I assume the gun is overgassed with the can on it.

The factory mags are crap. I have 2, 16" 556s'

As far as ammo,,,,I shoot MK 262 ammo in mine with a KAC NT4. Man, that is one high pressure round right there and it runs fine. Matter of fact,,I wish I could find the brass.

[fsteinba]

No issues with mine made from a pistol using AR magazines and Privi Partizan 55gr.

[bstew]

The factory sig mags that come with the gun are not good. Get rid of them use a quality AR mag and I bet that gun wont jam.

Brian Stewart
FFL/SOT

[zakk]

Man I really want one of these. Is it a strait bolt on mod? Kind of a buy the stock and put it together (with a stamp of course) deal?

[fsteinba]

It looks pretty easy...the pistol has a plug/cap threaded in where the buffer tube would be on an AR; remove the plug and screw in an AR buffer tube w/ stock - but I like that you can put a folding stock on the 556. ACE sells a hinge and a folding stock kit.

[zakk]

I like the regular sig folding/telescoping stock a lot. I'll have to check out the ACE though, thanks.

[the_assman]

i have one of the early pistol's that i sbr'd . runs like a top with any ammo in all weather .

[fsteinba]

I like the regular sig folding/telescoping stock a lot. I'll have to check out the ACE though, thanks.

I also prefer the Sig folding/telescoping stock that is on the Classic 556 rifle. Unfortunately the lower receiver is different and the hinge is part of the lower. The only way to put the Sig folding/telescoping stock on the pistol is to use the complete lower assembly from the Classic rifle. It's an easy swap, but expensive.

[Atlantajohn]

I have the 556 pistol that I am working on doing a Form 1 (current delay with local sheriff), and I love mine with no problems.

[zakk]

I like the regular sig folding/telescoping stock a lot. I'll have to check out the ACE though, thanks.

I also prefer the Sig folding/telescoping stock that is on the Classic 556 rifle. Unfortunately the lower receiver is different and the hinge is part of the lower. The only way to put the Sig folding/telescoping stock on the pistol is to use the complete lower assembly from the Classic rifle. It's an easy swap, but expensive.

Ahh didn't know that. Well for that kind of money I could get by with a CTR lol. I really know if I need a folding stock either.

[Kip42]

I was shooting winchester NATO 5.56, and rem .223 ammo with ar mags. I am going to shoot it some more and see what the deal is. It locks open like its empty and I saw another guys doing the same thing. I SBRed it from a pistol.

[ATCDoktor]

Here's a thread on the 556 forum about the OP's problem.

http://sigarms556.com/viewtopic.php?f=16&t=10183

It appears that the bolt stop pin and spring are the culprit.