Sig 551A1 – American Copy of a Classic

The Sig 550 has earned a reputation as being a high quality military rifle capable of incredible accuracy and reliability. Based on the timeless and battle proven AK47, the 550 and its variants are seen by many as a refinement of the Russian warhorse. Despite its sterling reputation for reliability and accuracy, the rifle hasn’t seen wide spread adoption in NATO countries. The 550 is used primarily by the Swiss military with a handful of special units and police forces outside of Switzerland using them on a relatively limited basis.

In 1978 the Swiss laid out the requirements for a rifle to replace the homely yet functional Stgw 57 rifle (sold commercially as the SG510).  The focus was on developing a modular rifle that would be immediately available in both rifle lengths and carbine lengths. Several rifles and cartridges were considered but in end the SG 541 and the 5.56x45mm (GP 90) round were adopted. The SG 541 was renamed the 550 and the legend was born.  By 1983 the decision to adopt the 550 and the 551, with the later being a carbine version of the 550 rifle, was made and by 1990 it as accepted into military service as the Stgw 90 rifle.

Sig 556 rifle

The original Sig 556 rifle was an ugly little spud that had little more than a passing resemblance to the Swiss made 551 rifle upon which it was based.

A handful of semi-automatic rifles were imported into the US in the 1990’s before importation ceased due to restrictions passed by the U.S. government. The rarity of the 550 rifles on the U.S. market drove the prices through the roof and before long they were selling for $10,000 or more if you could find one for sale.

Seeing an opportunity to capitalize on bringing the 550/551 to the U.S. market, Sig began work on a domestically produced clone of the famed Swiss rifle and dubbed it the SIG 556.  The U.S. built 556 took a number of design liberties which separated it from the original Swiss design including the use of standard AR15 type magazines and machining the lowers out of aluminum vs. using stampings.

When Sig USA introduced the original 556 rifle to the U.S. market, I was taken back by how ugly the little spud was. Nothing on the rifle looked right including the M4 stock and ridiculously shaped hand guards. The rifles languished on the walls at area gun shops — it was a flop. People were hungry for a proper 550/551 clone and they flooded the internet with requests for Sig to revamp the appearance of the rifle to make it look more like the original. This lead to the 556 Classic which sported a more traditional look but it still was an abomination that purists, such as myself, rejected. We wanted a 550/551 knock-off that looked authentic and used Swiss type furniture and magazines. Around 2011 Sig got the message and put the finishing touches on the 551-A1 which outwardly is a faithful replica of the Swiss made military rifle. I wanted to buy one but I had a slight hang-up with Sig by this time.

If you’ve followed my channel for the last couple of years, you’ll recall I bought one of the first-run Sig 556R rifles which is a derivative of the U.S. made 556 chambered in 5.56x45mm. This rifle appealed to me because it uses standard AK47 type magazines and fires the affordable 7.62×39 cartridge. Since the 550/551 borrows heavily from the AK in its operation, I thought the marriage of the popular Russian round and the Sig rifle was a novel idea. I bought one.

SIG 556 Classic

Sig’s second attempt to appease the 550/551 hungry public was the 556 Classic. With a proper forearm and a stock that more closely resembled its Swiss counterpart, it was almost what we wanted. Note the early buttstock that both folds and is adjustable for length of pull.

After taking the 556R to the range I quickly realized I had made an expensive mistake as the rifle was an absolute wreck. The fit and finish was horrendous. The rifle malfunctioned multiple times every magazine and with a wide variety of ammo. The magazines locked into a bare aluminum lower receiver which quickly caused heavy erosion when using steel magazines or polymer surplus magazines with steel inserts. The fact Sig let this rifle out into the wild in such poor shape was shocking to me, so much so I swore off Sig products for several years thereafter.

Sig got the message that the 556R was a complete mess and moved to quietly remedy the serious flaws of the 1st generation guns. Without much fanfare Sig released a generation 2 rifle that corrected the faults of the original but they didn’t change the nomenclature. Unless you know what you’re looking for, buying a 556R can yield a rifle that works great or one that falls apart with little use. Fear not, within the first couple of magazines you’ll know which one you bought.

At this point you likely understand my reluctance to buy the 551A1. I didn’t want to get stuck with another lemon and forced into dealing with Sig customer support (another story altogether). So I waited to see how the 551A1 was accepted by the market place and what new owners were saying about the rifle.

Overall the feedback from owners was positive. It seemed that the 551A1 was a solid rifle, so a couple of years after its introduction I bought one.

My initial impressions after taking the rifle out of the box were mostly favorable. The finish was nice and the rifle looks enough like a real Swiss made 551 that I was giddy about calling it my own. Sure, the hand guards rattle and the stock feels a bit flimsy, but rumor had it that these were exceptionally accurate rifles. That, and they accept the “Swiss style” magazines which are AK like in operation. Given the extremely rare nature of the original Swiss made 550’s on the U.S. market, this was as close as I was ever going to get to owning one of these classic military rifles.

Sig 551-A1 group

With 62gr PMC XTAC ammo my Sig 551-A1 prints 3″+ size groups at 100 yards, far from impressive performance.

I took the rifle to Young’s Long Shot to see how it stacked up against other rifles in my collection in the accuracy department. I only had two types of ammo to play with, a 55gr PMC ball load and the 62gr PMC XTAC (M855). Both have given decent accuracy in other rifles, usually around 2″ to 2-1/2″ at 100 yards. In the 551A1 the best I could muster was a 3-3/4″ 100 yard group with the XTAC. I wasn’t impressed. I plan to revisit my accuracy testing using match grade ammo down the road and hope I achieve better results.

After spending a few range sessions with the rifle I noticed that it made plenty of noise while handling it. With electronic ears on, which enhance your ability to hear under normal conditions, it became incredibly annoying. Picking the rifle up to shoot it, walking around with it, doing anything other than standing still with it in your hands would bring about a barrage of rattles. The hand guards have a good 1/8″ or more play in them, the upper and lower wobble around on the two pins that hold them together and the stock even wobbles side to side a little.  With this being my biggest complaint against the rifle, I plan on using some JB Weld on the hand guards and fashioning some sort of accu-wedge to take up the slop in the upper/lower receiver fit. I’m not sure how to shore up the play in the stock just yet, but I plan to do what I can to clean that up as well.

Given the hefty $1600 MSRP price tag on the Sig 551-A1, I’m more than a little disappointed in the sloppy fit of the rifle. I should’t have to resort to garage gunsmithing to whip my pricey 551 clone into shape. I’m also not impressed with the accuracy so far, but I’m optimistic if I find the right load I can wring out at least 2 MOA from the rifle. The Swiss 550 is claimed to be a 1 MOA capable rifle however I don’t believe the US clone is going to be capable of such accuracy regardless of the ammo used. We shall see.

Right now I’m able to look past the fitment issues and I’m hopeful I’ll wring better accuracy out of the rifle once I find a load it favors. Perhaps I’m so forgiving because I so desperately want to own a 550/551 and I know this is as close as I’ll likely ever come barring an unexpected lottery win. I will hang onto the rifle for the time being and see if I can massage some of the kinks out with a little elbow grease and JB Weld.

Be sure to watch the MAC video on the 551-A1 for more information about the rifle.


MAC is an avid shooter, former MCSF Marine, NRA member, Oath Keeper and is commissioned as a Colonel by the Governor of Kentucky. Known for his videos on the Military Arms Channel, he also writes for The Bang Switch, for Shotgun News (Be Ready!) and freelances for Guns & Ammo. MAC has been a life long shooter who has an interest in all things that go "bang" but gravitates towards military type firearms.

More Posts - Website

Follow Me:
TwitterFacebookGoogle PlusYouTube

  • Richard McKenna

    i have found PMC ammo to be sub par. Its very inaccurate, usually under powered and their match stuff always seem to have dud primers. Can you test it with some m855 from Federal? Not the best in accuracy, but better than PMC, and many people have tons of that ammo sitting around. Thanks

    • MAC

      I’ve not found PMC to be particularly inaccurate in my testing. While it’s far from match, it hasn’t given any worse performance than M193 ball. Out of my Tavor it shot pretty well as a matter of fact. However, as you note (and I mentioned) the use of match grade ammo should tighten things up a bit but I don’t think I’ll reach the 1 MOA mark.

      • Richard McKenna

        Well maybe its my ARs and Savage bolt, but I have found PMC quality control to be similar to Wolfs. Good for plinking, and thats about it. PPU is on the opposite end of the spectrum however. I would like to see how PPU fairs in the rifle. I get sub-moa groups out of their 69 grain from my Savage. The Stag 8 loves the 55 grain Remington UMC. And my Spikes 16″ DI loves 62 grain anything lol. Except wolfs, but it fires it. I guess i just cant trust the South Koreans to make good solid ammo for civilians yet. (for those who didn’t know, thats where PMC is from)

  • icepick37

    Here’s hoping you get a bit of a Cinderella story out of the thing. The fit seems disappointing indeed. :/

  • Alpha

    As a user of the swiss made SG 550 in the Swiss Armed Forces I am very disappointed about the quality of the US clones.
    If you are ever near Switzerland you should come by and we go out shooting.

  • Pingback: Sig 551A1 – American Copy of a Classic | The Gun Feed()

  • 33AD

    If its match-load snobby, is it truly a battle rifle (even as a clone)?

    This is a shame. I want one but agree for the price it should have a better fit/finish/accuracy.

    Thanks for the review – will check out the vid.

  • Rande

    Hey Mac, a thing that might be causing the rifle stock’s looseness is the screw that connects it to the receiver. I have a Sig 556 Patrol mocked up as a 552 and the first thing to fall off was that little screw. If you fold the stock you should be able to see it.

    • MAC

      The slop is in the lock itself. If it were properly deigned it would be self adjusting (like a Galil).

      • Rande

        Gotcha, Sig-USA at its finest.

      • Jon Simper

        I have two 550-A1 rifles. One of them is the 10″ SBR. Neither rattles like yours does on the video (I ran to the safe right away after watching the video). I have a little looseness in the hand guard only on the standard rifle, no rattle on the SBR (maybe do to the hand guards being different). Both stocks are tight as well as the upper/lower receiver lock up.
        On my 556 the stock is tight but there is a little play between the upper & lower. The play in the hand guard was horrendous and I had to address that.

  • SspOfAnwärter

    Currently a soldier in the Swiss military. If anyone has questions about the actual 551, I can offer my input (with some delay of course)

  • Matthew Bosch

    Mac, did you shoot with irons at all? My 551 had a loose rail. Front and middle screw were about to fall out. I figured something was up when I took rifle out a second time with aimpoint comp m4 sighted in previously and the thing was shooting terribly. I shot a better MOA with my bore sighted MI flip ups that I had just mounted before going out the second time. This didn’t make sense until I inspected the front and middle rail mount screws were very loose. Loctited all three in and resighted the the rifle with a trijicon 1-4 accupoint with a larue mount and the moa dropped considerably. Threw the comp m4 on and ar just to test it and it functioned fine. Used xm855f. Just a thought. I just picked up a SAM7SF-84 so I’m interested to see which shoots better for me.

    • MAC

      I did shoot with irons however my rail wasn’t loose. I checked that after firing a few groups. I know in the past Sig has had issues with the rails on the 556 line.

  • Jake Hellmann

    MAC, find some original 550 furniture, perhaps it will fit better. i think cogunsales has a lot of Swiss stuff

    • MAC

      The furniture is outrageously expensive. I’m not willing to invest another $500+ in furniture. I believe the rifle should be well built from the factory at the $1600 price. If Sig were selling these for $800 I would be inclined to invest more money into improving it.

      • Jake Hellmann are willing to JB weld a $1600 rifle to get the upper/lower to fit properly lolz

        I agree with you for the price you paid it should be perfect. I was about to buy one for these off gunbroker but thanks to your video I’ll pass. Sig should take note, its not like you some schmuck with 40 subscribers and 100 views….

  • Pingback: Sig Sauer 551A1 Rifle | The Gun Tube()

  • Drmaudio

    Well, at least it’s purdy.

  • PLPswiss

    Too bad you couldn’t get your hands on a 550… If you visit switzerland one day, you’re welcome to try it out. There are truckloads of them here ;-)

  • Amadeus76

    Disappointing… I was giving some heavy thought to picking up a SIG in the future but after this review I’m not seeing how a rifle marketed as the improved AK is worth it. Especially at that price point.

  • G43nut

    As a 551-A1 owner I agree with everything listed other than my stock is rock solid.

    For the front hand guard I cut a rubber o ring in half and pushed it into the gas block. Now the fit of the handguard is solid. As to the accuwedge I just put a foam ear plug under the locking lug when closing the upper and lower. All slop removed.

    Should you have to do this with a rifle of this price? No but like you it is as close to a 550 as I will get.

  • JC

    I have to disagree with you on the 556, while I never shot one, I always thought it was a good looking rifle!

  • TL

    Mac, would you recommend a Windham AR-15 over this for my first 5.56 rifle? I have always been in love with everything Swiss and the especially the Sig 550 for that matter. I was going to get one of these last year before the AWB scare. I held off until everything cooled down here and now I think the Windham would be proper for my first 5.56, your thoughts?

  • sbfcapnj

    I bought a second generation 556 SWAT for a bajillion dollars. I haven’t been 100% impressed with it. It runs fine. Solid shooter. I just want the AK style mags and the 550 look. The quad rail on my 556 is complete overkill and it makes the gun much heavier than it needs to be. Fortunately for me, though, the 556 SWAT does not rattle at all. It feels snug. Maybe I’ll buy a 551 A1 and just put my 556 upper on it. Hah!

    Great video, though. I might look for one of these. I doubt I’d be able to cover the cost of a new one by selling my 556, though. Thanks for the video.

  • Brybear

    I agree with MAC. I was lucky enough to shoot a sig 552 semi-auto version. It is nothing like my sig 556. NOTHING. Grant it, the mechanism is different in the 552 but this was converted with the 553 kit. My sig 556 is way over gassed. I have the classic patrol. Now like MAC says if you got it for $800, getting the troy rail, troy sights, would make it worth it. I disagree with MAC and the PMC. IF the PMC ammo is the new patch, it is garbage. To not whip out physics here, but they made the batches too fast during the scare. The so called “steel core” aka harder core in the bullet (62grain) is suppose to be placed properly during the “annealing” process. It isn’t in my PMC. PMC 62 Five five sixers in my sig 556 4MOA, I purchased 1000 rounds in July. PMC from before 1.5 MOA. No key holing but something is wrong. Hornady steel cased still 1MOA. Remington 2MOA. Something is jacked up with those new patch PMC in my sig. I will have to check it out in my AR.

    • MAC

      My XTAC is about 1.5 years old and it’s printed 1″ groups in several different rifles. Even with match ammo the best my 551A1 can do is about 3″, which is horrific.

    • Jeremy Day

      Are you sure it’s over-gassed and you don’t just have the gas key set to adverse? The gas key should be in the vertical position. And the mild steel penetrator in M855 is not placed during annealing. Annealing is a heat treatment done to the neck of the brass case. This is why military surplus ammo has discolored case necks.

  • Gremlin

    The Sig 550/551 rifles have achieved MYTHICAL status, despite there being only 500 or so examples in the US and most reviewers/shooters have never seen one never mind fired one. Can the 551-A1 be worse that a ‘real’ awesome Swiss rifle that nobody’s ever got their hands on? One youtube reviewer who has both judged them approx the same, other than collector value.

    Accuracy testing with non match ammo is dubious at best, but note the Swiss 550 issue rifle has a longer barrel, and Swiss soldiers are not issued with PMC ammo. One wonders how much better it could be than an AR given they both have ‘pencil’ barrels though.

    Wiggle in the stock lockup? Since the stock is a Swiss made part, and is self contained (attached to the receiver with a single pin), the lockup wiggle can only be due to the Swiss stock itself, not the US components.and cannot be attributed to US manufacture of the rest of the rifle. Mine is fine. Perhaps yours is defective and could be replaced by SIG? Likewise, you may not like the trigger feel, but it is constructed identically to the Swiss ‘mythical’ one, so that would be a feature of the Swiss design and not a US ‘clone’ defect.

    Receiver looseness – mine is fine, but military carbines are not constructed to the same tolerences (for good reasons) as target rifles, as evidenced by US AR-15s popular fix for this problem, being the ‘receiver wedge’ or a foam earplug, If SIG won’t address your receiver looseness problem then perhaps you would benefit from a ‘Zurich Wedge’ from, a euro designed device designed to take the slop out of the Mythical Swiss rifles (what? they have slop too??) – worth a shot for under 20 bucks.

    Handguard looseness – I heard the US gas block was slightly different than the Swiss, and since I have a Swiss one on my 556, I can check if that is the culprit, with both US and Swiss handguards… I agree that Swiss furniture costs a bundle, but you have the Swiss stock already, the pistol grip is US, but no problem with it, and real Swiss handguards can be obtained from Sig for about $80, so no $500 upgrade needed here…

    Maybe the rifle needs a *little* attention to perform best – why not give it a go and see? I’d like to see an updated review in the future.

    • MAC

      Fortunately for me, a friend of mine has a Sig 550 and I’ve been able to examine it quite closely. The differences between the Swiss rifle and the US rifle are significant in terms of methods of construction, quality and attention to detail. I’m sure there are those out there that would disagree with me, but I have no biases nor loyalties to any brand or company that would interfere with my judgement.

      I wanted to like my 551A1, I was extremely excited to get one after seeing them at SHOT Show when they first hit the market. If this weren’t true, I would have never invested so much money into one. Sadly, mine is little more than a novelty as there isn’t any way I would consider taking this rifle over others in my safe for personal protection. Will I keep it as a range gun? Yup, it’s as close as I’ll ever get to owning a real one.

      The stock does have Swiss markings on it, or so it seems. The magazine does as well. Neither are of what I would deem to be exceptional quality, I would say they’re marginal at best. The magazines fall short of the quality I’ve seen in 5.56mm Bulgarian made AK mags for example. If they weren’t so expensive, I would torture one a bit to see how it held up. Perhaps that’s the subject of a future video. The stock seems to be lighter weight and of a different feel than on the pre-ban 550 my buddy has. Perhaps the Swiss have changed the recipe over the years, and not for the better.

      The handguard is absolutely horrible and in a future video I will show what needed to be done to take the considerable play out of it. I have seen airsoft toys that exhibited higher quality of construction.

      As for the accuracy, I’ve fired everything from Federal Gold Medal Match to the PMC out of it (even some Wolf) and it has yet to produce a (5) shot group tighter than 3-3/4″ which is abysmal. I have AK’s that are more accurate, in 7.62×39 no less. Speaking with my gun writing friends at various IMO publications, I’ve learned their rifles also demonstrated horrendous accuracy with a wide variety of ammo. So it doesn’t seem to be a phenomenon unique to mine.

      I tried to order a Zurich Wedge for my rifle when I discovered the poor fit, However OnceSource was sold out at the time. Thanks to your post I was able to place an order today since they’re now back in stock.

      As for the play and comparing it to an AR, I don’t have any AR’s in my collection that have such a significant amount of slop between their two halves. I own mostly Colt rifles, but I have a few Stags, Windhams, LWRC’s and others — all of which exhibit far superior fit and finish when compared to the 551A1. None of them require a wedge to keep them from moving around in my shoulder when taking aim or firing.

      In short, it’s a neat novelty and range gun but aside from that it’s little more than a conversation piece that I pull from the safe when talking about notable firearms of the 20th Century.

      • Tucson_Jim

        First of all, I would like to remind people that Switzerland is one of the world’s most affluent countries. Their guns are used for DOMESTIC self-defense, and not hauled all over the world, or battlefield. The current estimated cost of building a military SG 550 is approximately $3000, a non-starter in the cheap-a$$ US market.

        One of the easiest ways to drive down manufacturing costs, is to revise the tolerances of the specifications. If someone knows what they are doing, it can actually improve quality, while cutting costs. However, as someone with 30 years of manufacturing experience that includes tool, gauge, and fixture design… there is a world of difference between what you learn in school, and what is actually needed in the field (or factory).

        This is why your faucet leaks after 18 months, the PC Board in your fridge needs replacing after 2-1/2 years, your car needs the airbag and ignition switch replaced, and the nails back out of your house’s framing and break through the plaster board.

        I have a SIG R556 Classic (not 556R), it is as accurate as an M4, doesn’t rattle, doesn’t wobble, the trigger is great, and it has virtually NO vices. I love it, and wouldn’t trade if for anything in the world. But, the rotary-diopter is NOT Swiss quality, either.

        I am looking for another one, and am currently writing a very long letter to SIG to express my displeasure that they have done such a lousy job introducing and supporting what should have been a fabulous alternative to the AR platform. They also never offered it with a 20″ barrel… and then, they cancelled it because they did such a crappy job that killed its sales.

  • Rtaylor

    I am the owner of a number of actual SAN rifles (550, 551, 553), all are exeptional in build quality and accuracy. I am a member of the Swiss Rifle club in Calgary Canada and can report that with iron sights the actual Swiss rifle can achieve 3-4″ groupings at 300m using Swiss service ammo (5.6mm GP90). I think it must be remembered that the US SIG company is not the same company as SIG Switzerland. It is unfortunate the 551a1 is not the same as the SAN 550.

    • Gremlin

      It would appear the US Sig 551-A1 is capable of acceptable accuracy at 300m according to this shooter, whose criticisms seem mainly in comparison with his Swiss bolt gun:

      Quite good results, I think. He did change the rear sight though – to one that would accept target diopters.

      Honestly I think if the proiblems with MAC’s rifle are as described it should be returned to the manufacturer rather than tarring the entire line with the apparent faults of the example at hand. I’m afraid that comparing the 551-A1 to the Swiss guns and finding it to be a a poor copy, but then describing the identical Swiss made components as ‘marginal’ seems like an oxymoron to me. Send it back…nothing to lose.

    • PGT_Mini

      Sadly, you won’t be with those beautiful rifles much longer given the RCMP’s recent move. Wish there was an easy way to get them safely down to the US vs. having them seized and destroyed.

    • Jeremy Day

      Too bad the RCMP recently banned those rifles and you had to turn them in.

      • Kurt

        I v heard it takes for 5 years to clear out all existing stocks in CDN importers … so another 5 years to bang with them

    • Kurt

      howdy and hoi :)

      do you have any idea US made SIG 551 shoot as well as Swiss GP 90 ammo well ? while Swiss surplus ammo is between 5.56 and 223 rem . < not true 223 and 5.56 :) and another important thing is rifling of barrel ..Swiss army model Stgw are made in 1-10 and lately some P 90 are 1-8 but American 551 clone is 1-7 …?? so any ideas

      gruss aus LA Swiss Club

  • Hank Seiter

    I know I’m very late to this thread, but I own both a Sig 551, Sig 556, Beretta AR-70 and more importantly the Stoner AR-180 and the civilian version of the Stoner 63, the Robinson M96. I can authoritatively said the Sig 551 has nothing really similar to the AKM otherwise known as the AK-47 (the former used a stamped steel receiver and technically the latter was original manufactured in the late 40s and early 50s with a milled steel receiver and was a bit heavier.
    Other than the fact the AKM/AK-47 and the Sig 551 are gas piston operated, it is the Stoner AR-180 and the Stoner 63 which provided the design technology and engineering for the Sig 5XX series. And Stoner’s design had received NO inspiration from Kalashnikov’s creation.
    Eugene Stoner was an firearm genius on par with John Browning. His line of stamped steel 5.56 “assault rifles” are the softest shooting, robust, accurate and reliable weapon systems yet to date in my opinion. And the Sig 551 and Beretta AR-70 “clones” are no slouches either. One would be well served with any of those four weapons system but be warned, in original configuration the Stoner 63, Sig 551 and AR-70 have their own proprietary magazines and they typically cost between $40 to $60. Robinson Armament’s M96 uses the traditional AR-15/M-16/M-4/STANAG magazines but only about 3400 M96 were manufactured before RA stopped their production line (and parts support, btw) in favor of their newer Robertson Arms XCR which was designed to compete in the US military’s new 5.56 rifle trials. Stoner’s AR-180 uses a virtually identical magazine to the M-16 rifle but instead of using the traditional latch hole on the left-side of the magazine, it used a latch slit on the opposite or ejection port side of the magazine with the over-insertion bump on the left side removed while the square slot is still there. Also the slide stop bump at the rear of the magazine follower is milled down 1/8″. Other than that, externally the AR-180 magazine looks very identical to the AR-15/M-16 magazine and in fact uses the same follower except for the different dimension of the slide stop bump.

  • datimes

    I bought a 556R and then read the reviews. I was worried I made a bad choice. Called SIG and gave them the serial #. The customer service guy said it was a newer model and not to worry about the mag well. I’ve been using Russian bakelite mags and the rifle runs great. Dislike the sloppy fore grip but have gotten used to it.