SIG Sauer 516 .300 Blackout SBR

SIG Sauer had this nifty short barrelled SIG 516 on display at AUSA ’12. I hope this design (with or without the short barrel) goes on sale to the public.

So many companies have developed compact AR stocks but are reluctant to sell them to consumers. One example would be the nifty stock featured on the Colt Sub-Compact Weapon (SCW). The SCW never went into production and the stock design never went on sale to consumers.

[ Many thanks to Lionel for the photos. ]

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.


  • Supersonic

    Very impressive. If it’s just as reliable as the previous 516s have proven to be, I think we have a serious winner.

  • Esh325

    Kinda neat I guess.

    • gunslinger

      in for the responses

  • Avery

    That stock almost looks like the one used with the HK416C PDW, as well. I think it’s the sliding rail/rod supports that made me think of the connection.

  • bbmg

    Very pretty!

    FN needs to pull its finger out and engineer a P90 that can chamber 300 Blackout…

    • Denny

      Are you eluding to blowback being able to handle .300BLK? I am very doubtful o that. If you implement any sort of locking to it, you will be likely out of parameters for P90 (such as weight and size).

      Besides, was there any attempt to design AR based weapon in bull-pup format?

      • HSR47

        I think he’s talking about the overall ergonomics of the P90, not necessarily the size and weight.

        That said, while I think a top-loading bullpup in a useful caliber would be nice, the width requirement, as well as the requirement for a custom new cartridge with more parallel sides, would make it mostly useless.

        I could certainly see it being scaled up to 9mm or .45 though, but I doubt that would really be much more practical either, at least outside of ammo pricing/availability…

      • bbmg

        I used the term “engineer” to allude to the fact that the action obviously would not handle 300 blackout pressures as is.

        FN has a 5.56mm bullpup in the FN 2000 that could readily be converted, but it would be nice to have the P90’s unique magazine configuration in a harder hitting yet quiet format.

      • Denny

        To bbmg: 5.7×28 also operate with decent pressure… not far away from 300blk:

        It is the Impulse (average force times time of pressure duration) which makes the difference. If something like that should be made out of P90 you’d have likely a ‘frankenstein’. I cannot imagine such long shot loaded in transverse direction to barrel.

      • bbmg

        Well… someone seems to have made it work for a shotgun:

        As to blowback and larger calibres, it was made to work even for 20mm cannon:

        How compact the result weapon would be though is questionable, maybe the F2000 is a better idea after all.

    • DW

      you mean F2000 in .300 BLK?

      • bbmg

        I meant the P90, obviously the F2000 could be converted with very little work.

      • noob

        a p90 style transverse top loading magazine for .300BLK would make the weapon about three inches wide and hold about 40 rounds. Development costs could be upwards of $20 million to get to prototype stage.

        hmmm. I am unconvinced…

      • Duray

        .300 Blk is engineered with tapered cases matching the 5.56, meaning it needs a curved mag, ie STANAG. In inline, topfeeding stick mag full of tapered cases would be a bit sloppy from a reliablility standpoint, no?

    • W

      …Or you can have a Magpul PDR in 300 black out

      • Giolli Joker

        That WOULD be great…

  • Giolli Joker

    Very nice!
    Am I wrong or SIG AR carbines are all piston driven?
    I wonder if this one is and they engineered the action to work with subsonic loads… I’ve read that most attempts in this direction failed…

    • TCBA_Joe

      The 516 and 517 series are piston driven. Their M400s are standard 16″ barreled carbine gas DI guns.

      • Giolli Joker

        So this “should be” piston driven… I’m more curious now…

  • Aftermath Gun Club

    I like that the SIG516 lower’s single point sling mounting points were moved to the receiver extension/stock mount instead of removed entirely, in order to accommodate the sliding stock arms.

  • KC

    I think companies are reluctant to sell those stocks to consumers because of:

    A. the proprietary short bolts they use are the only things comparable with it or;
    B. they’re worried someone will put it on a rifle length gas system and mess it up

  • HSR47

    So it’s basically their take on the Honey Badger….

    • TCBA_Joe

      Seems like this was designed in response to the same tender that the honey badger was built for, not as a response to the honey badger.

      I doubt Sig went “that looks cool lets copy that”. More likely that both Sig and AAC got the same contract requirements and ended up with a similar product.

      • Charles

        It’s worth mentioning this is gas piston operated as well. The AAC Honey Badger is not.

  • Mike Knox

    I can’t picture what’d happe if a swiss went drinking with yanks. Maybe something like this?

  • Lance

    The rifle is a bit too small for me a regular SIG 516 would be more comfortable. .300 is a nice caliber if your into suppressors but 5.56mm is still more economical and flatter shooting now.

    • Trebor

      204 Ruger is very flat shooting so that may be best for you.

    • JoeBob

      The whole point of .300blk is for suppressing and short barrels…

  • Richard

    Short handy little rifle with more stoping power than machine gun in pistol caliberl nice idea. Being based on 516 should make pretty good.

  • Mabey

    I would love to see the .300 black out chambered in a C96 carbine or a modrenized version of the pistol with a quick change barrel.

  • W

    A awesome potential PSD/PDW SBR.

    300 black out is a awesome cartridge. very neat. I cannot wait to see it become more popular.

    • Big Daddy

      I think the .300 and 6.8mm are both better than the 5.56mm and should be in the US inventory over the 5.56mm. The 5.56mm round is outdated and no matter what they try and do to it the round will still be outdated. It will never match those two rounds for what they can accomplish.

      The troops should have the 6.8mm in a new rifle. The .300 should be for special circumstances and be available in quantity. Both the M4/M16 and M249 can be modified to fire the .300 very easily. The 6.8mm truly needs a bigger reciever to work in military aplications as with what LWRC is doing.

      • W

        I disagree that the 5.56 is obsolete given the newest advancements in open tip match ammunition, which makes the capable even up to 700 meters with superior ballistics compared to the Cold War era M855. One shouldnt judge the applicability and lethality of the 5.56 based on reports compiled when M855 was in use (although i find myself doing that every once in a while).

        Indeed, the M855 had its purpose: to shoot heavier armored Soviet motor rifle troops wearing body armor and steel helmets with M16s having 20″ barrels. When firing a 14″ M4 or 10″ Mk18 against malnourished developing country inhabitants? the M855 performs poorly. The Mk 262, Mk 318, and M855A2 are light years ahead.

        There is no doubt that the 260-280 sized cartridges are ideal for a combat cartridge…more so than the 5.56 and 7.62. While compromising niche specific unique advantages of either cartridge (such as the 5.56’s light weight and the 7.62s wider surface area), they effectively blend the attributes of both cartridges into a singular one. Whether its 6.5 or 6.8, or another equivalent, this family of true intermediate cartridges were far ahead of their time when they were first unveiled (see the 280 british) and ultimately shelved for dualist, extreme solutions to existing problems.

        I agree. We should have a 6.8 or similar sized cartridge that can potentially replace the 5.56 and 7.62 (for rifles, DMR, LMG, GPMG, and some sniper), keep the 300 win mag for precision snipers, 50 BMG for heavy weapons (and for fucks sake! get a lightweight heavy machine gun developed and in the field), 300 blackout as a replacement for submachine guns/CQB use, and a 9mm open tip match for handguns 😀

        one can only dream…

    • Big Daddy

      I agree, I also like the General Dynamics .338 machine gun. That fills a niche for sure between the 7.62 NATO or a 6.8mm GPMG and the 50 cal.

      The MK262 or any 5.56mm just cannot match the new 6.8mm round being developed by ATK and Federal and the LWRC SIX8. That is the weapon of the future IMO. I think you will slowly see a change over to the 6.8mm with the push from three or more companies who have dedicated themselves to this round. One country or more has started to switch, they are small countries. I think they are Jordan and Saudi Arabia, but I’m not sure at all.

      I think it’s just like the DOD just when everybody is saying they will stick with the 5.56mm they do a 180. Like they did with the 7.62 NATO. The DOD said that’s out round and the M14 is our gun, all of a sudden out pops or poops the M16. The trials for the new SAW has been going well so will it even be a brass cartridge?

      The 5.56mm is just not designed for short barrels, both the 6.8 and .300 are. If not a short barrel you have to go with a bull-pup. I think in the future ALL troops will be either transported by vehicles or aircraft, the days of the true grunt humping it for miles and miles is coming to an end.

      Yes once the ground has been taken you will have to do patrols so that means walking but until then it’s trying to get in and out of small doors and hatches which means a short weapon. And mostly fighting in cities, MOUT or CQB, maybe some jungles too, who knows what’s next on the map for the US forces?

      • W

        yeah i didn’t know anything about that new round until a couple of minutes ago. fascinating stuff.

        it would be awesome if our military took the step it should have taken back in the 1930s.

  • Big Daddy

    I’m sure a lot of guys that served in Vietnam had wished they were issued this instead of the M16. It seems like the perfect weapon for jungle fighting or CQB. I hope our SOF guys have these or something like it with suppressors to use if they need it.

    It seems like a great combination, just change uppers and nothing else and you have a much better weapon than the 5.56mm for a lot of jobs. It completely eliminates the need for the MP5 or any other SMG/PDW type weapon. More power, compatibility, quiet as hell with the suppressor.

    I would have much rather had this than the M3 I carried as a driver. Of course from what I understand when the M3 was made it cost the government $20.

  • scotty in tulsa

    loki guns in atoka ok make a stock very similar to that one, and it works great for a pdw. also having a short stock like that does not meanthe bolt is shorter as well.they gun they built for me has an m16 boltcarrier, and all internals are nico coated. thier “factory” gunis a pdw fullauto that has fired ove 30,000 rds without ever cleaning. i have seen it. look them up and awnswer your own Questions ! you have the right to your own opinion, but not the facts !!!!!

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