Sig 556 rifle review

Stevedcross @ The Gun Blogs has just posted a review on his new Sig 556 rifle

I brought home a new baby. A brand new Sig 556 rifle. Forward grip, stream light tactical light, HALO sight. What a wonderful piece of engineering! I have as of yet not done any formal accuracy testing, but during the basic sight in session, the rifle was easy to shoot, minimal recoil, very steady, and shot well.

More here.

More info on the Sig 556 can be found at the Sig Sauer website

The SIG 556 features the same high-performance two position adjustable gas piston operating rod system engineered by SIG’s sister company Swiss Arms and marries it to a trigger housing that not only cuts the rifle’s weight by a pound but is designed to accept standard AR magazines. The SIG 556 features a 16″ military grade cold hammer forged barrel, chambered in 5.56mm NATO, with a twist rate of 1 in 7″. The flash suppressor uses a standard .5 x 28 TPI thread pattern, ensuring compatibility with after-market accessories. The forearm housing the gas operating system is a vented non-slip polymer featuring the SIG TriRail design with three integrated Picatinny rails for mounting accessories. The optional flip up front combat sight is adjustable for windage and elevation.

More here.
Picture 6-4

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Tom R.

    I’ve been trying to sight in my 556 with no luck. I started with weaver mounts and a Leupold, then switched to a LaRue Tactical mount and a Zeiss Conquest scope. This thing fires the first round nice, and after that they start walking all over the place. If I fire ten rounds thirty seconds apart off snad bags at 100 yards you can’t cover the group with a dinner plate. It’s nuts. Anyone have any ideas about this thing, or is it just a dog? I even tried another shooter and three types of ammo.

    Thanks, Tom R.

  • ChanRa

    I picked up the Sig 556 with Eotech holo plus 3x optics about 8 months ago. I brought the optics to about 3 MOA at 25/100 yds. After 21 years of daily use of the M-16 I can’t help but compare these two weapons. If I had to stay tactical and on the move for more than a week the M-16 is best for its lighter weight and part interchange. I’ve yet to try changing out parts on the Sig. I prefer the Sig’s feel and balance and the extra weight was easily overlooked in my tactical agression drills where adrenaline more than compensates. In fact, the weight helped me return to my target much easier. Like others, I also experienced several instances where the bolt failed to catch open after the last round. I’d be interested to hear from anyone who has tried a magazine other than the issued Sig plastic version. There appears to be a little play in the magazine when it’s seated. A remedy is desireble so I don’t have to wait out the possible hang fire issue on an empty chamber! What can I say? I don’t count rounds with an assault rifle. I also noticed some metal filing shards in the receiver and some bothersome wear on the bolt catch after my second outing when over 300 rounds were fired in about 10 minutes. Anyone else experieced that one? Extra lube ended that problem next time out. One very pleasing thing I found was how clean the lower receiver remains after firing. It is completely isolated from firing residue during cycling. I like that a lot. As a search and clear weapon through congested areas, my drills proved it reliable and easy to see through with the EoTech optics with both eyes open. Target acquisition was quick. I would recommend some shoulder workouts to reduce fatique during those potential long search and clear ops. The front end can get heavy after 30 minutes of continuous raised weapon tactics.

  • tyler

    yeah my 556 is a little weird also (its actually back at the factory right now) it was shooting nice groups at 100 yards but the were however WAY WAY low. so low infact i ran out of adjustment on every scope i have, trying to get it zeroed. hopefully sig will tell me what the heck was wrong with it when it gets back!! ill keep you posted. ive also heard of a few probelems like this from guys at three gun matches they said it has something to do with the rifling or something!!!

  • Zeus

    I find it very strange your having such problems zeroing your 556. At 100 yards with a basic Bushnell Trophy red dot I shot 1 inch groups with 55gr Winchester Q3131. When I switched to Privi Partizan 75gr Match ammo I shot even tighter groups like 3 shots that a quarter could cover. The 1 in 7″ twist barrel shoots the heavier bullets best. I tested all the ammo off a bipod and bench setup with a fwd vertical grip attachment as well. I did however have to adjust zero quite a few inches down from the 55gr zero for the 75gr to be on target.

  • SigdobetterQC

    I’m very disappointed with Sig Sauer. I was told rifle was in stock, paid with plastic and it took 3 months for my order to arrive. Funny thing is about 5 of us ordered at the same time and they got theirs 2 months before me. And yes this was before the elections. Finally, it (rifle) was sent to them to get it fix. One of the issues like everyone else is zeroing!!! It’s been 1 month and haven’t received any word on the status.

  • Uber Grease

    Well, thanks for the input on from the owners. I was really interested in these but I think Al the negatives I’m hearing now that I’m actually doing the research will point me in another direction. Disappointed but I will get over it.

  • Dave

    I have had a 556 holo for about a year. I think the stock holo sight is worthless. I sent in the original unit because it would not stay on target. The second one lasted longer but is now having the same issues. I have noticed Sig no longer shows the holo unit on it’s website. They are showing a red dot.

  • Folks, Sig is offering a rebate of $300 on the Sig556.

  • bird223

    Are you guys looking at your ammo. 1:7 twist is a 70 gr and higher bullet. Shooting 55gr bullets, good luck. My friend has the Sig 556 and that rifle is dead on and a lot of fun at all ranges from 50 yards to 200. but he’s using 62 gr bullets, it sucks with anything less.

  • Taz

    I ran Basic SWAT schools in 2008 & 2009 and some of the students from other agencies brought Sig 556 rifles. I had no previous experience with them but they looked and felt great and being made by Sig I figured they would perform well. Sadly they did not. In both classes we put students through 1,000 rounds of ammo in one day and both Sig 556 rifles broke after only 500 or so rounds. I don’t recall the exact problem but it was the same part in the bolt carrier group or buffer spring system that broke in both rifles. I would not buy one.

  • barehander54

    Hello sig owners

    I just bought a sig 556 classic rifle when i went a look i couldn’t decide on what I wanted I’ve had a couple of buddy talk about the Sig556 so I ended up buying one thought it was a little bit pricey thought that maybe that it was a better rifle I always hear pros and cons about rifles so it made it really hard to pick I did like the way it looked, got the diopter rear sights the gun dealer kinda persuade me a little bit now seeing these blogs after buying one I’m not so sure if I made a right decision now I shot about 300 rounds since I got it bout 4 days ago I know i’m having a really hard time zeroing the rifle with iron sights at 50 yards its want to shoot low right seems like no matter how many times I move it still hits the same spot what the hell, today I got it as close to the center as i could everything that I’ve been reading is that people are not happy with there 556 I’ve never had a Ar so I can’t tell which is better dose everybody have problems with there Sig. I thought Sig made good firearms now I’m wondering if I should sell it and get a bushmaster or something. What good is a rifle if it doesn’t hold up when you need it the most If there’s anyone with 556 classic e-mail me tell me what you think are all there rifles junk or is it something that maybe your use to a different style weapon also want to know if it will shoot any Ar Mags the factory ones are way to expensive

  • Robert

    I would almost bet the zero problem is due to people using 55gr bullets. The 1:7 twist of the SIG is gonna send those things flying all over the place. Go with a heavier bullet and you should marked improvement. Good luck!

  • Peter

    I have to agree with Robert here – shooting with 55gr rounds sends the rounds everywhere 62gr or better and you start seeing *much* tighter groupings on your shots. Performance with 77gr ammo is unbelievably superb – far tighter groupings than my AR at over 200yds.

    This holds true for pretty much any rifle I’ve ever shot with a 1:7 twist – they are designed specifically for stabilizing 70gr or heavier rounds.

  • Robert

    I went out tested a bunch of different ammo after my last posting. I fired 55g, 62g, 69g out of my Sig556. The 69g shoots awesome, i was doing .5 MOA with my 4x Leupold AR on top. The big surprise is that I was having no problems hitting a steel plate at 300m even with the 55g. The SS109 62g shot just fine too. I would still try your zero with 62g+ and if it still doesn’t work for you …….well…I think it might the shooter??? Also, try making your zero at 25m, I think you will like you bullet path much better.

  • Bill

    I have been watching this thread. I too have a zeroing problem with my SIG 556 ER purchased in late 2008. Rifle sat in closet until Sig came out with new diopter sights. Took it to the range in June ’10. It will not zero. Elevation is ok but front sight is all the way left and rear sight is all the way right and still the groups are 3″ to the left – @ 25meters(82feet). There is no more windage adjustment remaining in the sights. Sights were installed correctly. I don’t believe its the ammo, it is a rifle problem. Used 55gr Lake City, Federal, PMC and for comparison PPU(in a Wolf labeled white box). Grouping of shots is fine with any of the above ammo, but the groups themselves are off to the left in my case. Using heavier weight bullets may improve group “tightness” but I have serious doubts that my (and others) zeroing issues will be solved by changing bullet weights. I believe this is one of the SIG556 “lemons” that came out of a certain production batch. Other owners are apparently experiencing the same issues.

  • Tharsh

    I picked one up Friday. put an Eotech on it and headed to the range. target started at 20 mtrs. First shot was 3 inches low and 1/2 inch left of center. I shot a follow up to baseline the first and hit the same hole. Walked the target out to 30 mtrs, cranked the Eotech four clicks. fired on dead centered still low. Cranked up 16 clicks and first shot was bullseye, fired three more all in the black at about one inch spread. I was using sandbags and lake city 855. I shot 100 rounds. Had a blast. Second shot follow ups are really easy. I took the target out to 50 yds and hammered it. The trigger alone makes a huge difference. I think the weight helps even out recoil of which there isn’t much. For grins I disassembled the weapon to learn how and to check it out. Chamber really clean, gas tube took a little solvent and a few patches, wiped up everything, greased the bolt/hammer section and put it back together. I need the 3x magnifier to get out past 50mtrs. My eyes aren’t what they used to be. Overall this is a fine weapon. i am keeping my colts and armalites but until I win the lotto and can afford a LaRue the Sig is gonna be my play toy and primary home defense weapon.

  • mike

    got a sig 556 ,is it common for the spent cases to get dented when they are ejected

  • juan

    yes, it happens to all of them.

  • Bama Fan


    I was having the same problem with my Sig 556, could not get it to shoot consistence groups and it would not recycle either, about every 3rd round would hang up. I swapped rounds to 5.56 Nato BVAC 75 Grain rounds. That seemed to solved my problem. Recycles fine now and shoots 1-2 inch groups at 100 yards.
    The Ammo makes a lot of difference in these rifles. I tried all the major brands before I found one that works. Good luck finding an ammo that your Sig likes.


  • Larry

    I have 3 Sig pistols and that is why I bought a Sig 556 Swat. Problems, yes.
    1. Jams – answer from Sig: Did you clean your weapon? Yes, I answer. What ammo are you shooting? 5.56 I answer. How many grains? 55, I say. Well,

  • Larry

    I got cut off before, sorry. Sig informed me that the 556 is designed for 62 grain NATO ammo, not .223 or 55 gr. 5.56. They also said that the brass will get beat up during extraction. They said not to use reloads and that the extracted brass cannot be reloaded after being shot from the 556. My Sig has a pattern 3 times larger than my old AR15. It is heavier and the trigger is heavier. It may be a great combat weapon, but for my money, I will not buy another one. I have a Rock River, a Panther and a 30 year old Colt AR15 that will shoot circles around it. Style over substance seems to be Sig’s program.