Sig Sauer P556

[Review] Sig Sauer P556: Yep, that’s a pistol…

Oh boy…a “pistol” in 5.56! What a cool gun, I thought as I picked it up to look it over. Loaned to me by a good friend and former county deputy, I couldn’t wait to get some rounds downrange through it. I had always wondered about the need for a short-barreled, buttstock-free 5.56 gun, but after looking this one over and then shooting it, I can see its purpose(s). This is one gun to have with you when you are in deep doo-doo – it will take care of a situation. Even though the gun has been discontinued by Sig, there are still guns out there if you look for them. Sig does also make current models in this configuration, in different calibers.

Uses For A “Baby AR”

Yeah, I said it. ‘Baby AR’, indeed, I hear you say. Why in the world would anyone want the front 2/3rds of an AR-15-pattern gun? What about the stock? How can you shoot the thing without something against your shoulder? Well, that’s what pistol braces are for. I tested a short AR-type gun earlier (technically, an “other” firearm according to the ATF) – you can read that here. That Troy Industries gun was fun to shoot, to be sure, and the brace really helped. But – how would you use a gun like this P556 (with or without a brace)? I could see a few scenarios…

  • You want a “bug-out” gun to go into a bag or other carrier and it needs to be small, but powerful;
  • You are looking for something to defend your house or property with;
  • You need something potent that you can carry in your truck or car;
  • You want something smaller that shares magazine compatibility with your full-size AR;
  • You need a gun that would be powerful enough to dispatch larger 4-legged predators but small enough to keep in your ATV while roaming your property;
  • You want a range toy that would be truly unique

OK, I know a couple of these uses are a bit of a stretch, but you get the idea. With a proper sling, this gun could go with you on those “long explores” (as Winnie-the-Pooh calls them – I have 9 grandkids…). Or, just leave it stored with a magazine or two until such time as you need it in a hurry, in your house. I guarantee that any two-legged home invader with any sense at all who gets a glimpse of this gun will not want to hang around to see how THAT particular situation will play out. With the addition of a brace, the gun becomes eminently usable and practical. You will have a greater likelihood of accurate fire being directed downrange than if you shoot it without a brace.

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Here is the gun with the butt stock folded…

Sig Sauer P556 folded stock

To Hunt, Or Not to Hunt?

What about hunting? I know, that’s not the primary purpose of a gun such as this one, but it could work. Again, adding a brace makes sense here. If you are the type who lives out and has access to land (whether yours or someone else’s who has given you permission), you could conceivably take down the occasional coyote or other fur-bearer, as they’re called. Granted, this gun would most likely not be a 200-yard coyote whacker, but the last pair of coy-dogs I saw were exactly 103 yards from my front yard…that translates into a do-able shot for a braced AR pistol, in my book. Just practice at different ranges – that’s the fun part.

I could certainly see this gun being used to dispatch groundhogs and similar beasties. What would need to happen before any of this could take place would be for you to find the right optic. With a red dot, I could see taking game out to 75-100 yards or so. If you mounted a scope on the gun, that range would extend. I do understand that, by mounting a scope or other large optic, you are negating the handiness factor of the gun. Mounting a scope on the gun would turn it into a rifle, of sorts, and render the ability to throw it into a small bag all but null. Here’s what I could see – mounting some kind of low-or-no-magnification optic on it, and putting a folding brace on the back. You could fold the brace (creating a smaller package to store), and yet still have the advantage of a decent sighting system when you unfold it to shoot. Funny, evidently my friend felt the same way because that’s how his is outfitted. Anyway, these points are just my two cents’ worth on the usefulness of such a gun. These 5.56 pistols do have utility – you just have to find out how one could work for you.

On The Other Hand…

As we all pretty much know, the main purpose of a 5.56-caliber pistol such as this is not hunting, but protection. Given the current climate around the country (this is being written at a time when protestors are taking to the streets, burning businesses, bombing police stations, etc. and when hurricanes are threatening destruction to our southern states), I would think some-such gun as the P556 might be a useful investment. This gun would make an ideal PDW. As far as the AR platform goes, I know I’m glad that I have an AR carbine with multiple magazines if I need it. Heaven forbid that I would need it, but it’s there anyway. So goes the rationale for the P556.

Let’s take a look at the specifications. I always like to put those close to the top of my reviews because I know that some readers, like me, want to check out the numbers before going on to the rest of the story. So, here you go…

Caliber:5.56 x 45mm NATO
Action Type:Semi-auto -- long stroke gas piston-operated rotating bolt
Barrel Type:Cold Hammer Forged
Barrel Length:10 in.
Rifling:1 in 7 in.
Flash Suppressor:A2 Type
Forearm:Alloy Quad Rail
Weight w/out Mag:6.7 lbs.; as tested, 9 lbs. 13 oz.*
Operating System:Full Length Gas Piston, Rotating Bolt
Trigger Pull:5 lbs., 15 oz. as measured
Forward Assist:No
Dust Cover:No. The bolt handle is attached to the side of the bolt and the bolt is not top-charging like traditional ARs
Overall Length:20.5 in.
Sight Radius:18.1 in.
Mag Capacity:30-round standard STANAG NATO magazines – one included
“Real-World” Price:~$1000

* The gun had two lights, a red dot, a magnifier, iron BU sights, a sling and a folding butt stock attached.

A Few Highlights

One interesting feature of the Sig P556 is its action. It does not use the typical AR-type action, with a buffer spring. Instead, designers opted for a long stroke gas piston which activates a rotating bolt. This type of action is similar to that in an AK-47, and needs no buffer spring. Therefore, you can put many different styles of folding braces on the gun easily since there’s no buffer tube sticking out the back. A long-stroke piston tends to aid in accuracy. A typical AR short-stroke piston hits the bolt carrier group fairly hard while the bullet is still in the barrel. This conceivably could, in theory, cause lessened accuracy (although in reality I’m not sure how much difference you might see). Another more easily-verified advantage of the piston is that you don’t have dirty gases blowing stuff back into the carrier. This method of operation should help the gun to run a bit cleaner.

Another plus are the handguard rails. As you will see in the photos, there is a lot of area on which to mount lights, lasers, etc. That’s the advantage of the pistol format. You can hang many doo-dads off the gun like you can do with a rifle or carbine but still have it able to fit in a backpack or go-bag, making it the best of both worlds. Fold out the brace, pull the gun to your shoulder and you have a decent substitute for a full-size AR long gun in a package easily transported.

One final thought – the gun’s weight. When you pick it up, you’d swear you were picking up a “regular” AR rifle or carbine. This is no featherweight. The advantage of that is the fact that some recoil is siphoned off. It’s one thing to read, above, that the weight is 6.7 pounds; it’s another to have that weight in your hands (especially with all the accessories installed). There is no butt stock to grab onto (if you don’t install a brace), so all that weight is forward. It does help the thing settle onto a target easily, for sure. This is just my observation, so take it for what you will.

Here are a few photos I took. I left the sling on – I thought it added “something”, not sure what. This is one interesting gun, to be sure…

Sig Sauer P556 right profile

Sig Sauer P556 left-middle
Folded butt stock

Sig Sauer P556 right side

Sig Sauer P556 buttstock

safety trigger of the Sig Sauer P556
The safety is ambidextrous – we lefties appreciate that. Note the flat trigger, as well.
Sig Sauer P556 front

One light below the other one, with the iron front sight up top at a 45-degree angle.

rail on the Sig Sauer P556

Sig Sauer P556 with light
Two lights are better than one…
Sig Sauer P556 flash-hider
Flash hider (standard A2 style) and flag…

Sig Sauer P556 flag

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Shooting Results

I shot a few targets with the P556. It was fairly easy to shoot from the bench with the stock folded out, against my shoulder. It was basically similar to shooting an AR carbine-length gun.

The gun’s 10-inch barrel was loud, to be sure. I’m used to my 16-inch AR – granted, there wasn’t a great deal of difference between the two but it was noticeable, even with hearing protection. The gun’s weight soaked up what recoil the 5.56 rounds generated, which isn’t much on a good day.

I loaded the magazine with some military FNM head-stamped ball. This was made in Portugal back in 1992, and I assume is NATO-compatible. It did go off with a prodigious “bang.” Here is the best target I shot…the group is low and left, because that’s the spot where the red dot was adjusted for.

target shot with the P556

I didn’t attempt to further adjust it, since it wasn’t my gun. The red dot installed on the gun had a magnifier (obvious in the photos) that could be moved out of the way for close-in shooting. At any rate, the ammo went into two rather long, ragged holes on the target illustrated here. I was pleased with that, since I had never shot this gun before and probably would never do so again. Plus, we know how accurate AR-platform guns can be and this one, made by Sig, should be no different.

When I pulled the trigger with the brace against my shoulder, the gun jumped but not as much as some lighter-weight ARs have when I shot them. All in all, it was fun to shoot. (And, no, I didn’t try shooting from the hip with the stock folded – I’m no John Wayne. Being a lefty, I usually end up with hot brass crossing in front of me if I’m lucky and not bouncing off me when I shoot such guns from the hip… not much fun, that).


What did I think of this pistol? Well, I’m old school and when I hear the term “pistol” I tend to think of a gun that is held in both hand and has a barrel of 5 or so inches. I still have a bit of trouble seeing what looks to my eyes an almost-full-grown AR and calling it a pistol, but that’s just me. I understand the ATF has their rules about what constitutes an AR-platform “pistol” – I just am old-school, as I stated. But, that doesn’t mean an old dog can’t learn new tricks – I’m not a Luddite. These short guns have their place. As Tom Beckstrand said in the September 2020 edition of “Guns & Ammo” magazine, “The AR pistol with an arm brace represents the most useable ballistics horsepower in as small a package as possible.”

With the stock folded, this gun would fit in a suitable bag, backpack, or trunk and would certainly deliver superior fire power if called upon to do so. I can see a pistol like this definitely ruining a scumbag’s day if he were meant on harming someone. Just the presentation of the gun might be enough to have him reverse course. At least, that’s my opinion. This is impressive-looking hardware.

If you are looking for an(other?) AR, you might want to check this gun out. Even though it is not shown on Sig’s website, I’ve seen them for sale online. This is no cheapie – expect to pay at least $1000 for one. But, the gun should do everything you need it to and last a lifetime. Placed by your bed (where legal, of course), this would make a good home-or property-defense weapon. Just make sure you know what could happen to your sight and your hearing if you touch it off indoors.

The “Baby AR” has a purpose, or several of them. They are worth investigating, to be sure. If you’ve had experience with one, please comment below – we’d like to hear what you have to say about them. As always, keep ‘em in the black and stay safe!

  1. Mike– I don’t own one of these guns but I do own a Kel-Tec PLR-16 in 5.56 caliber and it is fully decked out with lights,laser,mini red dot sight,single point sling,and fore ward assist hand stop on the hand guard just behind the light-laser system. The whole system only weighs 5 pounds and with the muzzle break in place there is almost no recoil and very little muzzle rise. At 18.5 inches it is very concealable. With the green laser sight it is very accurate at 50 to 100 yards from the hip. It doesn’t need a folding brace to shoot well and is not set up for one. The article was very interesting on the P556 but I would rather have the PLR-16. That extra 5 pounds on the P556 adds up to 5 extra 30 round mags to me. Thanks for a great review. Bill

    1. Billy, yeah, I get it. The Kel-Tec is lighter, and generally gets good reviews. I’m glad yours works so well for you. Thanks for writing!

  2. Great article, thanks. I personally went with the Springfield Saint AR pistol and mounted a quick release 2-7×32 scope and AR sights I took from my Sig 516.
    The pistol is extremely accurate, well built and a lot of fun. How accurate you ask? Clover leafs at 100 yards and a 12×14″ steel plate at 4oo yards off a bipod.

    1. John, looks like you’ve got a winner. The Saint guns are very popular and are accurate. The 400 yard results are interesting, for sure. Thanks for writing!

      1. Had to follow the dust trails to see where it was hitting and adjust from there. If I remember I had to aim high and left. Cross hairs weren’t even on the actual target. It was just a “let’s see if it can be done.” Not something I’m going to try to prefect.

        1. John, as long as you’re satisfied with the results, that’s all that matters. Sounds like you have it figured out. Thanks for replying.

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