Sig Sauer Ships Carbon Fiber 516 and M400 Rifles

Sig Sauer recently announced on their Facebook page that they’ve started to ship their new SIG516 and SIGM400 Carbon Fiber rifles to their dealers. Both the SIG516 and SIGM400 rifles use free-floated carbon fiber handguards and come with a carbon fiber A2-length fixed buttstock. Both rifles also come with a 2-stage match trigger and 30 round Lancer L5 magazine. The SIGM400 is a direct gas impingement AR while the SIG516 makes use of a short-stroke gas piston system with a with 4-position gas valve. The SIG516 rifle (pictured above) weights in at 7.1 lbs without a mag and retails at $2,504. The SIGM400 rifle (pictured below) also weights in at 7.1 lbs without a mag and retails at $2,132.


Ray I.

Long time gun enthusiast, archery noob, Mazda fan, Sci-Fi nerd, Whiskey drinker, online marketer and blogger. My daily firearms musings can be found over at my gun blog and Instagram.

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  • Paul Epstein

    …How, precisely, does the piston-operated AR with the full length rail weigh exactly the same as the direct impingement version without said rail?

    • dp

      Oh craps… you beat me to it as I was typing (chuckles).

    • Nathaniel

      Weight the same? If you go over to Andrew Tuohy’s AR-15 weight calculator (here:, you can absolutely make a lighter railed DI AR-15. Here’s my example:

      4/5ths of a pound lighter than the SIG offering, not bad!

  • ben

    I am curious and serious. Other than to kill people or destroy inanimate things…how exaxtly can you use this? Constructively?

    • wetcorps

      Do you mean this particular rifle or any firearm? Also, what do you mean exactly by “constructively”?

    • Steve Truffer

      The same way every other firearm is used? Most are not for “killing people” (leave that discussion about cops & such for ttag). Most are for punching paper, taking game, and as a “just in case” defensive tool.

    • 11b

      Constructively? Maybe in a match? Maybe outside plinking? There are many constructive uses for a firearm.

    • CJR

      An AR-15 is pretty explicitly designed as a weapon – a tool for fighting with. I find that purpose to be entirely constructive.

    • bbmg

      The universe is gradually slowing down isn’t it? And will eventually
      collapse inwardly on itself according to the laws of entropy when all
      thermal and mechanical functions fail, thus rendering all human
      endeavor ultimately pointless…

      In this wider context, why should law abiding firearm enthusiasts continuously be asked to justify their interests? If we had to eliminate all the non-essential aspects of life and just plug people into respiration and feeding outlets it wouldn’t be much fun for anyone.

      I don’t buy the “Ah but knitting makes stuff which keep people warm, shooting kills people” argument either. In the United States, you are almost 4 times as likely to commit suicide than to be murdered. That is a horrifying statistic which most people are happy to ignore, because our society places a bigger premium on *feeling* safe than on actually *being* safe.

      • dp

        You seem to have a philosophy day my friend – ))))
        It is good to put existence in greater prospective; it clears visors a bit.
        As on killing, lets call in ‘conversion of souls’. Its more palatable.

        • bbmg

          No, just woke up on the wrong side of the bed 😉 and tired of people asking why I *need* to have guns. People don’t need to ride horses, but they still do and an average of 20 or so of them die doing so in the US every year. Go and ask them what is so constructive about riding horses.

          I could go on ranting but I have more *ahem* constructive things to do with my time, there’s a dismantled revolver in a box by my feet that needs some TLC.

          • dp

            I understand – and you have your point.
            Relating to the subject. Once I had one of my guns out to redo bluing. With measure of confidence I just took gun to bits and gave them to vendor.
            When I got back the bits, out of sudden a wave went over me – I had a fit of panic that I will not be able to put it back together in absence of documentation. Well, eventually I did. Those mental states….

          • bbmg

            I know that feeling… but thanks to the internet you can find guides to reassemble almost any object these days 🙂

      • n0truscotsman


        our society is more dedicated to enforcing the magical, elusive “right” to “feel safe” than they do supporting existing, enumerated civil liberties (funny thing, there is nothing in our founding documents about “feeling safe”)

        Collapse inward? nah. I’m praying for the comet before then 😀

        • bbmg

          It would be in the founding documents if there were founding mothers as well as fathers I can tell you 😉

          • n0truscotsman

            ha 😉

    • whodywei

      Bed room role play maybe ???

    • RocketScientist

      “I am curious and serious. Other than to kill people or destroy inanimate things…how exaxtly can you use this? Constructively?”

      Very simple answer. I’ll break it down for you

      1) “how exactly can you use this?” – You grip the rifle firmly with your dominant hand on the pistol grip and your support hand on the forearm, with the buttstock placed firmly against your shoulder. Placing your cheek along the top surface of the buttstock, you align your eyes so that they have lined up the front and rear sight with each other. At that point (assuming properly zero’d sights at the appropriate range) the projectile will shoot wherever the sights are aimed. Maintaining this eye-sight alignment, aim the gun in a direction that you wish you launch a small projectile at high speed. When you are satisfied with your aiming, place your index finger on the front surface of the trigger and slowly and smoothly pull it backwards. Assuming there is a round in the chamber and the safety is set to ‘fire’, after a few pounds of pressure and a few millimeters of travel, the gun will fire and shoot a projectile in the direction you have aimed the gun.

      2)”Constructively?” This is a very simple matter of choosing whatever you consider a “constructive” direction to shoot the gun. You see, the gun is merely a tool (like a hammer or a computer). It only does whatever you tell it to do. So YOU have personal responsibility (a foreign concept to many) to ensure that the tool is used for constructive purposes. As for ME, I consider killing (bad) people and destroying inanimate things (as well as killing animate non-human things, aka hunting) as “constructive uses”. But you can use it for whatever YOU consider constructive (or not use, as appropriate). That’s the beauty of liberty. I can have my opinion and you can have yours. And ideally neither one of us tries to force our own on the other.

      • bbmg

        In the UK, you need a good reason to own a firearm. Imagine that! Aside from the fact that most desirable types of firearms are completely impossible to obtain:

        “A shotgun certificate won’t be given or renewed if the chief officer of police has a reason that you shouldn’t be allowed to have a shotgun under the Firearms Act. Or if they don’t think you have a good reason to have, buy or acquire a shotgun.”

        That paragraph alone is the reason people without an interest in firearms should purchase a shotgun.

        Apologies to SIG for not discussing their beautiful rifles.

        • FourString

          “Completely impossible” is a huge stretch. It is VERY possible to own a shotgun here for sporting purposes. Do you know how many Winchester SX3’s are floating around here? (These are very capable shotguns)

          • bbmg

            Sorry for the UK bashing but I was not stretching. Show me your legally owned M1911 or semi-auto AR-15 and you will have made your point. Heck you can’t even own an air pistol over 6 ft-lbs, some Americans check their facts 😉

            You’re right to say that moderators are not as heavily regulated in the UK, but they are legal for individuals to own in the US in most states. It’s certainly easier for many Americans to obtain a suppressor legally than it is for most UK individuals to obtain a FAC.

          • FourString

            oiiiiiiiiii cantcha see i’m tryin’ ta be optimistic here—-T-T *SOBS PROFUSELY* —-FTS (╯°□°)╯︵ ┻━┻

          • bbmg

            Come to America, it’s great. I can’t convince you as well as Doug Stanhope can:

        • FourString

          I agree with nearly all of your points, but there is no need to bash on the UK. We can own rimfire semi-automatic rifles, bolt rifles in just about any calibre, moderators (suppressors–not even Cali residents can do this!) for hunting purposes, and pump/semi-automatic shotguns just fine……………….. sigh.. what Americans tend to believe these days…

          • Brine!!!

            I would say he wasn’t bashing the UK. Just bashing the government of the UK and the ridiculous laws they enact.
            We have a very long tradition of doing this in the US.
            As well as bashing our own government and its own ridiculous laws.

    • David

      Think of it as a form of insurance. Some insurances are actually considered property. The monetary value in case of loss being the asset with equity in the form of personal ownership attached. If you think owning insurance to manage the risk of losing a valuable asset in your life is important, then consider the following.

      Firearms are a property form of insurance in a way. Almost like a nation’s military. Most nations don’t expect to be invaded or have catastrophe befall them, but it just might happen despite their best efforts, and that’s why most maintain a military. It’s a form of insurance. I don’t expect to get in a car accident every time I drive a car, but I certainly wear a seat belt every time I drive, not because it’s the law, but because despite my best efforts, I just may end up in a wreck and I want to manage my risk in a mature and considered way. When I live in society I own a firearm. I don’t own one expecting to have to defend my life or another’s, and to have to represents a catastrophic event in one’s life. But despite my best efforts, it might just happen. It’s a form of mature, considered risk management.

      Owning a firearm as a form of risk management is ethical by its very definition. Lets not even get into the political application of force, or credible projection of force by an armed citizenry as a part of checks and balances.

      If you think mature and sensible risk management is a constructive and positive outlook for members of society to have for that society, then firearm owners are exemplars of that notion.

    • Steve

      To protect the Constitution

      • invisible empire

        Ironically a lot of the cops that are on TFB are trying their best to destroy it.

    • st4

      If you find some lettuce and mayo, it would make a mean sandwich. Serious.

    • ieattodestroy

      Mr.”ben” You have brought to me something very concerning! When I eat I usually chew, when i chew… its usually pretty destructive! Should we all stop eating??

    • Zachwillb4everfree

      They are used for self defense as all guns are used.. Noone is argueing that guns weren’t made for self defense and ultimately the survival of life, liberty and the pursuit of happiness. I bet the Jewish people the nazis were rounding up and slaughtering wished they were able to defend their families with rifles like these. even with these semi automatic rifles (1 trigger pull =1 projectile… Like a hunting rifle with a much less powerful projectile with a larger magazine) many people would still have died. And the odds would still have been extremely stacked against them. We may not be in danger of such atrocities today but it is very important that we preserve those rights for our children and their children. Because the evil you fear will always find it’s place in a seat of power. And forgive me but is your argument really based on whether people can use rifles to kill people? Lol it’s baseless. It blows my mind how people still don’t get it.. It isn’t the rifle, its the person behind it. And it’s the good upstanding citizens of our country that have prevented wars here on homeland soil and kept this country free. Guns shaped the world you live in and without them you wouldn’t have the platform we call democracy upon which you stand today to express your oppinion. also I believe shall not be infringed was stated very clearly in our constitution. The same constitution that gives us our rights we know and love. Each of the rights bestowed by our bill of rights plays a crucial role in preserving our freedom.. now what could you possibly say that trumps freedom and the preservation of our ability to defend our loved ones from any danger that arises? And who are you to tell anyone what they need to do so. we aren’t the enemy. I respectully ask that you reevaluate your position. I know you probably have good intentions but look at the big picture and ask yourself at what cost.. I digress.

  • dp

    I have one techno observation: piston model had full length railing while DG is just partial. I’d assume it related to heat dissipation along the length of tube. My question would be: how about rest of 99 different makes of ARs? They do not look the same. I am sure to whip out some opinion about it.

    • Steve Truffer

      Screw (DI) ARs. I hate getting gassed every time I pull the trigger. I’ll stick with other rifles (AK74)

      • Gassed?

        • Steve Truffer

          Tried a few mags through an AR pistol. Got a snoot full of hot gas & burnt powder everytime I pulled the trigger.

          • Hunter57dor

            were you trying to snort ejected brass or seomthing?

          • Steve Truffer

            Nose to charging handle, eye over the bore, just as instructed.

          • nadnerbus

            It seems unfair to judge the design by the extreme of a pistol length gas system. It was never originally designed for that. A pistol, usually by definition, is held out at arms length anyway.

            I have never had gas in my face shooting a standard carbine or rifle length AR, 5.56 or .308. I have gotten a little gassed by my mini 14 and M1A though. Never shot suppressed.

      • Steve

        AR was a bad design from day one – hence the introduction of piston AR’s.

        AK’s forever (as in they’ll still be in use long after the last AR is made)

        • Steve Truffer

          Eh, I won’t say bad, just not my cup o Joe. Now if piston variants don’t give me a powder ‘stache , and a reciprocating charging handle is out there, for at or sub 1K… then maybe.

          • echelon

            No, it’s a bad design. It’s akin to having a car and you vent the hot, dirty exhaust gases back into the engine…

            In any other industry this would never fly…but in the firearms industry in the US? Standard Infantry Carbine and Rifle.

            Hilarity ensues…

          • Hunter57dor

            erm, look up EGR valves, they do just that.

            i do agree with you, DI is a terrible design, but just as you cannot compare a bicycle to a space rocket, you can’t compare engines and guns. different mechanical requirements.

          • echelon

            Yes not apples to apples…EGR, I suppose counts, but that’s really just a work around to get NOx supposedly removed from the exhaust and a whole host of other fuel related complexities…and there’s a debate ongoing whether EGR would even still be in use if it wasn’t government mandated but I digress…I think my example, though flawed still serves to illustrate my point!

      • n0truscotsman

        LOL yes.

        That is the solution to the DI vs Gas piston AR argument: Buy a kalashnikov.

      • vestee jackson

        what Steve Truffer said

  • raven

    That seems a little disappointing. The last AR I built (with low weight in mind) had an M4 profile barrel and came in at just over 6 pounds without a magazine and it cost me less than 1/3rd the price of this Sig… 7.1 pounds is not heavy by any stretch, but I expected it to be lighter with all the flashy carbon fiber…

    • mig1nc

      I agree. I was expecting much better than 7.1 pounds!

  • Joey Szabo

    Don’t feed the trolls…..

  • Michael R. Zupcak

    “I am curious and serious. Other than to kill people or destroy inanimate things…how exaxtly can you use this? Constructively?”

    Wow, when did we start getting anti-2A trolls reading TFB? Hey, I don’t care, more ad revenue for the gun enthusiasts that run the site!

  • ColaBox

    Will we be seeing a review of either rifle? Im curious of the difference between the carbon fiber and regular metal. Im especially curious about the stock.

  • 101nomad

    OOPs sorry, I came upon a political forum by mistake. .

  • vestee jackson

    You have to be retarded to pay more than $1000 for a rifle- ANY rifle.

    • JumpIf NotZero

      People in glass houses shouldn’t throw stones.

  • TheSmellofNapalm

    According to their website there’s a telescoping stock variant as well