New SIG SIG551A1

SIG Sauer will soon be shipping the SIG 551-A1. This rifle is essentially a SIG556 upper receiver, with Swiss-style furniture, combined with an aluminum SIG 551-style lower receiver. The biggest difference between the SIG 551A1 and the SIG 556 is that the former uses Swiss transparent polymer magazines instead of AR-15 magazines.

TACTICAL PRECISION, For 2011, SIG SAUER® is offering several variants to its tactical platforms. NEW to this lineup is our new SIG551-A1, chambered for the widely used 5.56 x 45mm NATO caliber using Swiss Polymer magazines. The SIG551-A1 features a distinctive swiss folding stock, and an M1913 rail for accessory attachment. The 16” barrel features four-groove rifling and a twist rate of 1:7”. The SIG551-A1 measures 36.1” but can fold to 26”, making it ideal for situations where maximum maneuverability is required. For Special Forces requiring an accurate, more potent rifle, chambered in 5.56 x 45mm NATO, the SIG551-A1 sets a new standard for dependable operation and function.

This rifle will mainly appeal to law enforcement or consumers, who would rather use the Swiss transparent polymer magazines instead of standard AR-15 magazines, and collectors.

Caliber 5.56X45mm NATO
Overall Length 36.1”
Length with Stock Collapsed 34.6”
Length with Stock Folded 26.0”
Barrel Length Without Flash Suppressor 16”
Operating System Gas piston, rotating bolt
Rifling Lead 1 in 7”
Number of Grooves 4
Muzzle Brake Fluted
Sight Radius 18.0”
Weight without Magazine 7.0 lbs
Magazine Type Swiss Polymer
Magazine Capacity 20/30
Trigger 2-Stage
Trigger Pull 7.5 lbs

NRA’s American Rifleman staff took the SIG 551A1 out to the range …

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.


  • slim934

    …..are there no transparent ar-15 mags available?

  • It’s about time. This is the rifle that American consumers have been asking for ever since the Sig 556 was released here.

  • Now if we could just get Sig to release the 550-1 rifle here in the States.

  • armed_partisan

    Ohh! I like it!

  • Flounder

    I like it but it would be a lot better if it could also use STANAG mags in addition to the swiss polymer mags.

  • KBCraig

    Swiss mags, instead of AR mags, = FAIL for the U.S. market.

    • Me

      By your logic …

      FAL mags instead of AR mags for US = Fail for idiots like you
      G3 mags instead of AR mags for US market = Fail for idiots like you
      Orlite mags instead of AR mags for US market = Fail for idiots like you

      I guess your just another moron that thinks all .223/5.56 chambered
      guns are AR’s.

  • Jeff

    Couldn’t they offer an adapter that can switch between proprietary mags and STANAG?

    I’m not familiar with the SIG 550 system but it seems to use a similiar paddle system as the AK… I recall way back when that someone was selling milled adapters for a STANAG magwell that simply clicked in

  • MarcW

    What’s wrong with the flash hider? The Swiss flash hider is integral to the barrel and nicely contoured. This just looks shoddy.

    • Me

      I’m sorry. You’re just an idiot. Removable barrel attachments are
      far superior to fixed. Are you even aware of the limitations of a fixed
      flash hider? Are you aware of the cost to machine that barrel with
      the fixed flash hider? Are you aware that the latest SG551 from SAN
      uses the same configuration as the 551A1?

  • Andrew

    Take my money

  • David

    Frankly, I don’t want this one to take STANAG magazines. If they sell their polymer mags too, then I’ll be happy. They already sell one that takes STANAG magazines, wouldn’t it be superfluous? I’m extremely happy because I was, in the next month or so, ready to take the plunge on a complete conversion which is very expensive.

    SIG can have my money.

  • Don

    Handsome rifle.


    • Me

      Ditto. Very handsome indeed.

  • cc19

    It’s about time indeed.

    Also, anyone complaining about the Swiss mags, get the 556 instead; that’s the variant that uses AR mags. That’s what it’s there for.

  • subase

    swiss mags can be joined together to create a super mag.

  • Flounder

    I bet if this is at all popular then someone somewhere will make an adapter for AR mags. But then again i’m bored with .223 rifles… There are a million AR variants and this seems like it is just another one of those. Don’t get me wrong I like this rifle but does it bring anything really new to the market that no one else does? Cause I like most people already have a .223 rifle…

    • Me

      AR adapter? Another AR platform? Yes!!! All weapons that fire the .223
      cartridge are simply AR variants!!! That’s why they should ALL use
      the best mag in the world. THE SUPER MEGA GALACTIC STANAG MAG!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  • Folkien

    If you want AR mags, get a standard 556. Heck, the trigger packs/lowers aren’t even considered firearms by the BATFE, so you can buy a 556 lower to use with AR mags on your 556-A1 upper and still have it legally be one gun. Probably way more reliable than any ‘adapter’…

    I’ve got mixed feelings on this one. Other than looks and the nice Swiss style stock, not much else going for it. Still the same barrel/gas porting, sights, and basic function of a 556… now with more expensive magazines! If the price is right, they might do okay. Otherwise, looks like a flop.

    • Me

      Looks like a flop? Is that your Internet Firearms Expert opnion?

  • Wait. So it’s effectively just a different lower for a Sig 556?

  • SuA

    Random thoughts from the owner of a ‘real’ Sig 551 SB:
    – Wow, they sure raped that flash hider & barrel profile. They should have at least make it look like a Sig 551 LB instead?
    – The front furniture is still not the real deal. I wonder why, must be a cost issue.
    – The sights look pretty shitty compared to the real deal, but I’d have to shoot one to tell for sure.
    – Real Sig mags on a $750 rifle? Really? Who thought this was a good idea?
    – Low profile mag release? Why? It was handy to have it long?
    – No sidefolding trigger guard? Sure losing charm quickly.
    – Alu billet lower? *shrug*
    – A1? Are you implying Sig Sauer USA made this thing better than the original? Sure doesn’t look like it.

    They just should’ve named them Sig 556 -whatever-, but marketing would not agree, I’m sure.

    • Me

      Since you own a ‘real’ 551 SB and have complaints about the 551A1
      flash hider, I wonder if you also have complaints about putting a
      supressor on your 551 SB? Give that a try sometime and get back
      to us so we can all hear how it worked out for you. All of your other
      comments seem to be based on what you “think it looks like”. Why
      don’t you go shoot the A1 and get back to us with comments that you
      can back up with something more than opinion.

  • cwc

    “The biggest difference between the SIG 551A1 and the SIG 556 is that the latter uses Swiss transparent polymer magazines instead of AR-15 magazines.”

    Small error; makes it sound like the 556 doesn’t use STANAG mags. Should swap the order of the rifles or change “latter” to “prior”.

  • Lance

    Looks fun! finally a Swiss Army style rifle for collectors. Now if they can sell there older 7.62mm NATO rilfe soon.

  • btr

    I see the magazines for the rifle are available from SIG for the low, low price of $82 each:

    Too bad “No quantity discounts are available.”

    • Me

      $82 dollars ??? You obviously haven’t learned to use google.

  • Nathaniel

    This would have been a welcome offering 5 years ago, but now, as SIG’s reputation tanks, it just seems desperate.

  • Beaumont

    Hey, SIG — why, exactly, would I want to buy a rifle that only takes proprietary mags?

    • Me

      Define proprietary. They are Swiss made magazines for a 550/551/552
      rifle. You sound like the “STANAG” crowd. I bet you get pissed off when
      you can’t put an AK mag into your Barbie Doll Dress Up AR-15.

  • jdun1911


    Yeah that’s pretty awful for magazine that probably cost $2 to make. $85 is a rip-off. For the price of five sig magazines you could have bought a nice pistol or a low cost AR15 upper or two to four complete AR15 lowers.

    Always look at the price of magazine before buying a firearm. That’s what gets most people at the end of the day.

    • The mags are $35, not $80, and are of much higher quality than AR mags.

  • Jay

    This guys from Sig Sauer USA really raped the reputation of the outstanding Swiss Arms rifles in US. 🙁

  • armed_partisan

    $82?!!! HOLY CRAP!!! Nevermind. I’ll pass. And they actually cost MORE if you buy the “Accessory Discount Set 1”, $87.50 instead of $82!

  • cc19

    I had my hopes up, but it should have been more like:


  • snmp

    If you have an Beretta_AR-70 ot an SG54X (By Manurhin or FAMAE) you could modding the SIG550 mag for use it in your rifle

  • Fred

    My local dealer has cases of mags and sells them for $45 each. The mags are great and the mag release is my fav over teh Ar and 556 style button. No clicp needed as the Swiss mags all clip togther by themselves. The gun is really accurate. Close as I’ll ever come to a real 550

  • KFin

    It’s a good ‘concept’ bring a truer SIG 5.56mm rifle to the US market, but even with the BF3 gamer market and all the SIG lovers out there at $2,000.00 plus $82 per mag, its only going to appeal to a select crowd who REEEEEALLY want a 551 esk rifle. I don’t see the sales figures on this rifle being very high, although I like it and may buy if the price drops. But with M-15s from Armalite sitting at a 1060.00 MSRP, with MidLength gas systems and easy and low cost customization (and they are far from the only AR manufacturer making it affordable)

    Just saying that I got a new AR10 (the new one that takes PMAG 20LRs) for 1399.00 and can out fit it with a tritium folding front sight, mags ($19), rear sight, and magpul polymer furniture (w/rails) for about as much or less.

    Lose about $600.00 on the price tag and this would be a hit being one of the most affordable piston drive tactical rifles and a SIG classic

    • Me

      You don’t see the sales numbers being very high ???? What are you????
      An “Internet Expert Firearms Marketing Analyst”????

      • Strat Man

        He’s pretty good lol !! – A Market Analyst !!