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The AR-15 pistol is the Rodney Dangerfield of the semi-automatic 5.56 mm world. It just doesn’t get any respect. It’s considered tough to shoot accurately, being too small and light to manage a rifle cartridge with no shoulder stock. Some claim that it has too much recoil, and other than being a range toy that eventually gets tossed into the back of the safe or sold, it has no real use (unless of course you’re planning to make it into a short barrel rifle). Being the unabashed SIG whore that I am, though, I decided to procure a SIG Sauer P556 pistol. My main reason for doing this was that I wanted an SBR and I wanted something to play with during the interminable wait for the ATF to get around to approving my application (eight months now and counting). At the time . . .

I didn’t own an AR-15 lower receiver that had not come as part of a rifle and due to the vagaries of the various federal gun laws, it turns out that while you can convert a rifle lower into an SBR, you can’t first convert it into a pistol to shoot while you wait.  You can purchase a full AR-15 pistol and later convert it to a SBR and you can purchase a stripped lower and build a pistol out of it, but since I would have to spend money anyway, I decided to go the SIG 556 route.

Why?, you may ask. Well, it’s pretty simple. The SIG 550 line of rifles uses a different operating mechanism than the direct impingement (DI) operation of the classic AR-15.  It’s operating system is also different from the short stroke piston designs found on other AR-15 style rifles including SIG Sauer’s own 516 line. I’d heard good things about the 550 line and wanted one in my collection, so I figured it might as well be my SBR.

The P556 is built on SIG Sauer’s well-respected SG 550 platform. The 550 itself employs a long stroke piston-operated rotating bolt locking mechanism reminiscent of Mikhail Kalishnakov’s original AK-47 design. As a result, one of the first differences that you notice between the P556 and traditional AR-15 pistols is the absence of the buffer tube protruding from the back of the gun. It’s not there because you don’t need it.

This has the immediate advantage of allowing you to use a folding stock to reduce the overall length of the rifle when transporting it or using it in close quarters. The original 550/551 line of rifles used a proprietary magazine, but when SIG Sauer brought the gun into the U.S., they developed the 556 model that used the standard STANAG magazines found in your favorite AR-15.

The long stroke piston design affords two improvements over the AR-15. First, as it uses a piston to reset the bolt rather than showering the carrier with filthy gas, the gun runs cleaner. Whether this makes one whit of difference to the reliability of the gun is a matter of significant debate. What it unquestionably does is to keep the innards cleaner than what one would find on a DI gun, so it makes maintaining your gun a bit easier.

The long stroke piston is also superior from an accuracy perspective to the short stroke piston design found on guns such as the HK 416 and SIG 516. Short stroke pistons strike the bolt carrier group hard to create enough momentum to cycle them back to eject the spent cartridge and load a new one. This high impact collision occurs while the bullet is still in the barrel and can result in a shock sufficient to throw the aim off just a bit. While this really doesn’t matter at the intermediate ranges the 5.56 mm cartridge is designed for, if you’re trying to make a long range precision shot, the short stroke piston design is not likely to be the most accurate system. A long stroke piston by comparison starts very close to the bolt carrier so when it strikes the bolt carrier, the shock is reduced.

Second, the long stroke piston is designed to remain in contact with the bolt carrier during the entire rearward travel, so it operates more as a gentle push rather than a powerful strike. There’s minimal if any shock to the rifle when the piston is operating so the rearward travel of the bolt carrier is much smoother and the chance of throwing off the aim of the gun much less. For this reason, the SG550 line of guns are well respected for their medium- to long-range accuracy.

If the long stroke piston design is so great and the AK-47/AKM/AK-74 line of rifles uses it, then why are AKs so inaccurate at distance, you may ask? The reason is that they’re manufactured to very loose tolerances. The SIG 550 line, though, are manufactured to relatively tight tolerances which is why they have accuracy that AKs can only dream about. If you doubt this, go shoot an AK side by side with a SIG 556R rifle that fires the same 7.62×39 mm round and you’ll see the difference.

The P556 is sold in two flavors; the first (and the one that I bought) comes with the Swiss-style hand guard. The other version (SWAT model) features a quad rail. Purchasers of the Swiss-style version get three short rails that can be mounted to the bottom and sides of the hand guard allowing you to mount a weapon light, laser, etc. Both versions have an integrated receiver rail which is where you can mount your optics.

Included in the box is SIG Sauer’s standard red dot. It’s not a terrible sight, just not a particularly good one. While I’ve never had a problem with one, folks who know tell me that in any given multi-day rifle class at the SIG Sauer Academy, at least one or more of these die. Then again, since you’re not likely to be popping targets 200+ yards away with this pistol, it should be fine for this application.

The P556 also features back-up iron sights which take the form of a permanently mounted front sight and a small rear sight that folds completely down into the rail.  These are BUISs in the truest sense of the word as the rear sight is a very thin piece of metal and wouldn’t likely stand up to daily use and abuse for very long, so you are going to want to use something else as your primary aiming device.

I initially mounted all three of the short rails to the hand guard, but it wasn’t particularly comfortable to hold, so I removed the left and bottom rails. Currently my gun is only running with the right rail, which is perfect for mounting accessories. I initially mounted my Streamlight TLR-2 laser/flashlight combo to the gun and it made the P556 an awesome home defense gun. The activation switch for the TLR-2 was in easy reach of my support hand without having to take my hand off of the rail. And the 10-inch barrel makes the gun very easy to maneuver in close quarters. Plus, once I had my laser dialed in, I was able to fire from the hip using the laser for sighting and consistently placed rounds in a reasonably tight grouping at 16 yards.

The P556 is capable of accurate fire well beyond 16 yards, but I had to transition to the red dot to accomplish this as the laser isn’t bright enough to illuminate my target beyond 16 yards when I tested it at the local outdoor range (and I ain’t about to test fire it in my basement.).  In an attempt to get better distance for the laser, I swapped out my TLR-2 for a Beamshot GB9000G which uses a green laser, but it didn’t really buy me much over and above the TLR-2. The activation of the light on the Beamshot isn’t as good as the TLR-2, so I will likely switch back in the not too distant future.



The P556 in stock configuration is plenty comfortable to hold. As I mentioned, I had initially mounted all three of the included rails to my P556, but that made the gun cumbersome to hold as the rails on a 10 inch barrel are so short that you have to wrap your hands around them and they protrude too far to make this very comfy.

Obviously, mounting a fore grip on the bottom rail would give you a good place for your hand, but that would make the gun an AOW in the ATF’s eyes, so so don’t do it unless you have tax stamp in hand. Instead, I went with a single rail mounted to the right hand side which is where I positioned my laser. Once I get my SBR paperwork back from that ATF, I may revisit that.

I ran into a problem when I discarded the SIG red dot sight for something else. I first tried my Lucid red dot, but the nuts that secure it to the rail are mounted on the right side and can’t be switched. Unfortunately, this gets in the way of the charging handle so that was a non-starter. I then tried my Strike Fire. That worked, but is still a bit on the cumbersome side. The ideal would be an Aimpoint Micro T1 red dot, but at $600, I’ll deal with cumbersome for a while. FWIW, the SIG red dot fit with no issues, but if this is to be used as a personal defense weapon (PDW), I’m not willing to trust my life to it.

Contrary to what I had been led to believe, recoil on this gun is rather manageable. When using the red dot, I can keep the back of the gun mere inches from my nose and when firing, the gun lightly taps me in the face. Rapid fire and accurate follow-up shots are child’s play. When you consider the fact that you’re loosing full-power rifle ammunition from it, you quickly come to grasp the effectiveness of this gun as a PDW.


One thing that I really like about the P556 is that it cheerfully accepts any 30-round magazine that I want to shove into it. I’ve noticed that on my SIG 516 patrol rifle, some mags take an inordinate amount of force to seat. Not so with the P556. Every single magazine snapped in, no problem. Several hundred rounds of milsurp penetrator ammo resulted in not a single misfire (and a huge, stupid grin on my face). And I’ve yet to clean my P556. As long I keep it lubricated, it runs like a champ.


Between the integrated rail on the receiver and the optional small rails that can be mounted to the hand guard, you can pretty much load this gun up with anything you want.  Uncle Mike’s makes a great little gun case that, while designed for sub-machine guns like the H&K MP5, fits the P556 perfectly. Bonus: you can even have a 30-round magazine loaded and locked into the gun and it still fits into the case. That makes this an excellent trunk gun, especially in places like New Hampshire where you can’t carry a loaded rifle in your car, but since this is technically a pistol, that prohibition doesn’t apply.


For a pistol, accuracy is pretty decent. The funny thing was that the laser enabled me to get a tighter group firing from the hip than I was able to manage using the red dot simply because I was much better able to brace the gun against my ample midsection. Nothing like a few extra inches of soft beer belly cushioning to keep the gun rock steady. My first group was fired with the red dot from 25 yards, and while nothing to write home about, would have kept every round in the bad guy and inflicted a fair amount of damage in the process.


Firing from the hip with the laser, I got an even tighter grouping on my head shots from 16 yards (the farthest I could still see the dot).


Now, it would certainly not fare as well as a rifle for long range engagements, but it’s not intended for that use. If the bad guy is beyond 25 yards, your chances of evading are much better. And if he is within 25 yards, he’s a corpse.

All of that said, however, I still see this gun as a niche weapon. If you plan to convert it to a SBR, it makes sense. The funny thing is that on the SIG 550 series rifles and pistols, it’s the upper receiver rather than the lower that carries the serial number. That means to convert it to SBR use, you register the upper receiver and then simply swap the pistol lower for a rifle lower (which you can mail order from SIG Sauer for $369 list).

If you want to do it on the cheap, you also have the option of removing the end cap of the pistol stock and attaching an AR-15 style buffer tube to which you can mount a standard stock. I’m going the route of the dedicated SIG stock because it folds and I want to keep this gun as compact as possible. Plus, the cost of the P556 plus the SIG stock is about $300 less than if I had purchased the SBR version of the 556 and I get to shoot it during the waiting period for my ATF paperwork.

SIG now offers the P556 in both Classic and SWAT flavors with the SB15 Stabilizing brace  pre-attached. Those versions cost about $130 more than the base model which is about what you would pay for the brace separately (but it’s still a good deal as it includes the necessary buffer tube for mounting the brace).

Beyond the whole SBR thing, though, this gun is a PDW and nothing more. As I noted earlier, its small size and awesome firepower make it a true nightmare for the bad guy in a home invasion situation, but you do need to remember that you’re firing rifle rounds, so undesired wall penetration is a risk if you miss.

While we’re on the topic of penetration, I decided to shoot my P556 side-by-side with my 16″ SIG 516 rifle and chronograph the results. While the six inches of reduced barrel size did make a difference, it wasn’t as bad as you might guess. I tested both 55 grain Fiocchi match ammo and 62 grain milsurp penetrator rounds. I shot 20 rounds from each gun and averaged the results. The mean speed of the 55 grain ammo was 2,806 fps while the P556 managed 2,431 fps, a 13% reduction. The 62 grain ammo out of the 516 clocked at 2,986 while the P556 managed 2,615 FPS for a 15% reduction in speed.

Is this a gun I’d recommend? That depends on you usage plan. It’s a wonderful platform on which to build an SBR and you can build it cheaper than buying a ready-made 556 SBR from SIG. I’ve never shot an AR-15 pistol before, so I can’t comment on how it would compare to one of those, but bear in mind that a standard AR-15 is going to add about 6 inches to the overall length for the buffer tube, which isn’t needed on the P556. If you are looking for a good home defense weapon or trunk gun that packs the power of 5.56 rounds in a short form factor, this is the way to go.

Overall, I like this gun. Given what I know now, if I were starting from scratch, I’d probably go for a 300 BLK SBR because it packs more punch and can fire subsonic rounds which is a benefit if you have a suppressor. Keep in mind that even with a 5.56 suppressor, the P556 is still going to be a louder gun as there are no 5.56 subsonic loads that I know about that will reliably cycle a semi-auto rifle and are available to the general public.

That said, 5.56 rounds are available for a lot less money than any 300 BLK rounds and the subsonic version of 300 BLK will cost even more than the supersonic ones. I have a reloading rig so I can build all the subsonic 300 BLK rounds I need. But if you don’t reload, you need to evaluate what’s available to you and 5.56 rounds are likely to be much more available and a lot cheaper than 300 BLK for the foreseeable future.


Caliber: 5.56mm /.223
Barrel: 10”
Sights: Sig Sauer Red Dot / BUIS
Finish: Matte black
Overall Length: 20.5”
Overall Weight: 6.3 lbs (without magazine)
Cost: $1,207 list, street price under $1,000

RATINGS (out of five):

STYLE * * * *
Say what you want about SIG Sauer, they know how to build nice looking guns.

It’s a pistol that shoots a rifle round. It’s better than an AR-15 pistol, but you’re still shooting a pretty powerful cartridge.

Hundreds of rounds through it over several months, never cleaned, never a misfire or a failure to feed or extract.

The Swiss style stock limits you a bit, but other than a laser/light combo and a red dot, what more do you really need to hang on an AR-15 pistol?

It’s great for what it does. If you have a need for it, you’ll love it,  If not, then just keep walking.

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  1. One of these days I am going to go through the PITA process of getting an SBR in Illinois, I already have a SIG-556 rifle that I love to death and a SBR pal to go along with it would be great.

    • Does IL require you to jump through extra hoops? Here in MD, the state basically devolves all responsibility to the ATF. Rather nice, in fact.

  2. Does anyone know if you can set up a trust for a SBR like you can for a suppressor?

    • Absolutely. In fact, the trust for a suppressor is exactly the same, if written correctly. I have half a dozen SBRs and a suppressor in my NFA trust.

  3. “If you have a need for it, you’ll love it, If not, then just keep walking.”

    “Keep walking”. Got it.

    • Yeah. I never could understand what niche things like this are supposed to fill, other than the “I think I want a 5.56 handgun” niche.

      • I dont understand how you think an SBR is a niche? Maybe you can fill us in on your infinite wisdom as to why a short barrel rifle (used by almost every elite fighting force in the world, even in 5.56) is just a niche, filling the whimsical purchase of a 5.56?

        • I never said I was part of an elite unit and I dont display my DD214 online either, but I spent 8 years in the Marine Corps and another 4 with the Army. One of my many MOS’s I received was as Armorer, and I can tell you that all of the various Elite units I worked with used Short Barreled Rifles as part of their standard armaments. Anyone who thinks a 10 inch AR15 pistol is niche should really think twice.

        • This is the United States of America… I live here… I don’t have any time-table pressing me to get in and “clear” occupied structures to reduce my expense to the taxpayers… I’ll park my ass in a high location with my PB&J sammiches and wait for the M/F B/G’s to come out to pee, flee, or eat… and pick them off with my M1A or FAL. If I get tired of waiting, I’ll entertain myself by shooting at them through the roof while my neighbors replenish my ammo supply. If uninvited guests are in my house, there’s an app for that, a 9mm with +P+ SJHP’s… if they are outside trying to get in… the M1A or FAL will shoot right through the walls and doors. Don’t need no show-toys with bitty barrels, slow bullets, and a huge muzzle flash.

        • JBEv…I think you’ve been closed up for just a wee bit too long. Although I loved your story, the theory that longer barrels make a more accurate rifle have been debunked many moons ago. Also, albeit a shorter barrel will slow a bullet down, it doesn’t slow it down enough to make any difference on whatever you hit within 300 meters. It may make an impact on how your hollow point opens up…but I don’t think in a SHTF situation you’re really to worried about that. Want to lug around an M1A or FAL…be my guest, they’re both great choices…but I want something more well rounded for civil unrest.

  4. A P556 SBR has been a bucket list gun for me for a long time. Put a UBR on it, maybe some MFI sights and a 1-4x scope… it’d be slick.

    But, let me be honest: the current factory iron sights on the 556(R) make me want to punch Sig in the mouth. Running non-magnified optics means you’re either 1) co-witnessing with a huge honking front sight in the way or 2) you’ve got it so high that you’ll never get a cheek weld without a riser. It’s 2013, guys, MAKE A FACTORY FLIP-UP FRONT SIGHT. They even did it before, but it’s the wrong height for the current popsicle rear sight. If they were feeling particularly saucy, they could even put some tritium in the front sight, like my Tavor’s flip-up front sight!

    The AR-15’s front sight is at least fairly svelte, so this isn’t such a huge issue on that platform.

    • Agreed! I love everything about my 556 SWAT17 except for the iron sights (well, the weight is a bit portly compared to an AR to be honest). I ended up pulling the rear diopter and pushing out the front fixed sight and putting on the short tritium Troy folding sights. Works with either an aimpoint or my TA31F (currently mounted).

      Also, if you are a reloader, the 556 beats the hell out of brass. Nice AK-style dent on each case and throws them WAY forward and a bit to the right. Makes finding your brass fun if you are shooting in the desert.

      I’ve been eyeballing a P556 for a while with the idea of an SBR. I didn’t know you could just order a new rifle lower from Sig so that now makes my thoughts creep that much closer to happening. Thanks for the info, OP.

  5. I have an Acog scope on mine and easily get anywhere between 3 and 5 inch groups from a bench rest at 100 yards and pretty consistently hit a 12 inch circular sawblade at 200 yards (with a loud satisfying gong for added bonus). But unless we’re talking about a zombie invasion, I think you are correct and best served to use this as a trunk gun or PDW for home defense. Fantastic right up!!!

  6. I’ve been looking at picking up a P556 but the US lower, though taking regular AR mags, is down right dreadful looking. With how masterful German design is I’m of the belief that it’s an intentional poke at the US market. Though with the new cheater brace models I just might see how hard it is to pull the brace off one and put it on a 551 lower.

    • If you decide to go the SBR route, Sig sells the Swiss style rifle lower as a replacement

  7. One thing not mentioned in this article. The p556 (or any 556 for that matter) kind of likes to eat up brass if steps aren’t taken to mitigate that.

    I know on my dealer’s p556 sbr, if you can hit them with bullets turn the gun sideways as the brass flying out will more than sting. 30foot arcs.

    Overall they are awesome guns and I really want one. The 556 classic swat is a heavy son of a gun.

  8. Great review! Using it for a SBR project is an interesting idea… I would love to see an update to this review in the future.

    Sadly, no SBRs in WA state… hopefully, that will change some day…

      • WA is almost perfect, excepting SBRs and SBSs. If they fixed that little problem, I’d give serious thought to fleeing there from MD.

      • Sorry, it can’t be a pistol in my slave state. Or rather, it is an illegal assault pistol, and was even before the 2013 tightening of the law.

  9. Ahh, your description of the “long stroke” vs “short stroke gas system is completely backwards and totally wrong. Just do an internet search for “long stroke gas system” and you will find many correct descriptions of the pluses and minuses for each system.

    • I don’t think it is “completely wrong” as you say. Please refer to the following wikipedia article: My description of how the two systems work is fairly accurate. Where the disagreement comes is whether the long or short stroke is the more accurate one. I stand by my comments but YMMV.

      • Re-read the article at the link you posted, then re-read how you described the “long stroke, vs short stroke” gas systems. The short stroke system has less felt recoil because it has more parts to spread the recoil out, op rod, tappet, bolt carrier. In the long stroke system the op rod is connected to the bolt carrier and will have more recoil but more postive loading, ejection etc… The article also states the short recoil system will be more accurate because of the spreading out of the recoil. Too make it even more simple, the short stroke system has two springs that retard recoil, on the tappet and one that effects the bolt carrier (towards the rear of the gun for the SKS and under the forearm for the M-1 Garand. The Long stroke system only has one spring, for the combination bolt carrier/op rod.

        • coondawg47 is right, Jim. From your post here:

          The long stroke piston is also superior from an accuracy perspective to the short stroke piston design … Second, the long stroke piston is designed to remain in contact with the bolt carrier during the entire rearward travel, so it operates more as a gentle push rather than a powerful strike. There’s minimal if any shock to the rifle when the piston is operating so the rearward travel of the bolt carrier is much smoother and the chance of throwing off the aim of the gun much less.

          From the Wikipedia article you cited:

          The primary advantage of the long-stroke system, beyond design simplicity and robustness, is that the mass of the piston rod adds to the momentum of the bolt carrier enabling more positive extraction, ejection, chambering, and locking; … The primary disadvantage to this system is the disruption of the point of aim due to the center of mass changing during the action cycle and energetic and abrupt stops at the beginning and end of bolt carrier travel.

          From your post here:

          Short stroke pistons strike the bolt carrier group hard to create enough momentum to cycle them back … This high impact collision occurs while the bullet is still in the barrel and can result in a shock sufficient to throw the aim off just a bit.

          From the Wikipedia article you cited:

          … the energy is imparted in a short, violent push and the motion of the gas piston is then arrested allowing the bolt carrier assembly to continue through the operating cycle through kinetic energy. This has the advantage of reducing the total mass of recoiling parts compared to the long-stroke piston. This, in turn, enables better control of the weapon due to less mass needing to be stopped at either end of the bolt carrier travel. These sudden stops on other systems disrupt the weapon’s point of aim …

          Your statements in this post are diametrically opposite the ones in the Wikipedia article you cite to back up your conclusions.

  10. For what it’s worth, the P522 (same form factor as P556 in .22lr) is a heck of a lot of fun, too. I’ve got an Aimpoint on mine, and yes that is an ideal (if rather expensive) setup.

    The main role my p522 plays is “range toy” for my own personal amusement, but it’s also my favorite gun to pull out when bringing newbies to the range. It’s got all the scary-looking features of an “assault weapon,” but is totally unintimidating to shoot. I’ve found it to be the perfect gun to help new shooters confront & get over any irrational fears about guns & shooting. It also makes a good prop for teaching them about the absurdity of gun laws & politics (like how simply attaching a VFG would be a felony, and how ridiculous the assault weapons feature list is when applied to the P522).

    • Hear, hear. I couldn’t quite justify the P556’s price for a “range toy” (especially last year) though I was intrigued. My favorite local shop had some P522s at a very, very good price and I figured it would be a good middle ground for the time being. Added a cheapo green dot and went straight to the range… it was insanely accurate, easy to shoot, ate everything, and was just barrels of fun.

      But the first time I went to the range with an “on the fence about guns” friend, it quickly became an invaluable tool for all the reasons you cite.

      Obviously they’re two very different firearms, and I still want the P556 at some point (even more now), but I don’t regret picking up the P522 at all.

  11. Wound ballistics-wise, a .223 at less than 2400-2500 fps is less than ideal, at least according to Fackler. A significant part of the wounding potential of the .223 is that the case will fragment when the round yaws in tissue, which adds considerably to the permanent cavity (each fragment makes its own permanent channel). Fackler’s argument is that even the M4 with a 14.5″ barrel launches a 62gr SS109 that falls below 2450fps within 50-75 yards, making the M4 not much more than a relatively accurate knitting needle beyond that point. His suggestion was to go back to the 55gr M193 load from Vietnam to get the velocity back up to what would make the .223/5.56x45mm perform as advertised beyond 75 yards.

    Since you’re not planning to use it beyond 25 yards you are probably in good shape, particularly if you use light .223 varmint loads for defensive purposes. Those are supposedly less likely to penetrate the walls in lethal fashion as well, which works for home defense purposes. Also not to be discounted are the flash-bang effects of firing a SBR at short range. “Deafening” and “giant muzzle flash” are features, not bugs if you can grab some eye-pro and ear-pro when you have to defend yourself.

    When I looked at the SBR-as-home-defense problem, my impression was that the 7.62×39 or .300 Blackout would have been better choices. You still get the magazine capacity you have with the P556, but you have a round that is less dependent on velocity-induced tricks to incapacitate. An AK SBR becomes basically a .30 Carbine, once you lose the velocity by shortening the barrel.

    I have a Kel-Tec PLR-16, which is similar to your P556, other than being unreliable. It is a safe queen, sadly. I don’t trust it to not misfeed when I might need it, I imagine I would feel differently if I had a SIG product.

    • One other ammunition option is soft-point bullets, but I agree that varmint rounds are probably pretty spectacular when they burst apart.

    • I would want to better understand the ballistics of 7.62×39 or 300 BLK with respect to what they do when they miss your target and start to penetrate walls. While you might believe that you will never miss at CQB ranges, the prudent person does the full “what if” analysis. For this reason, I’m not sure if I would personally ever use a 5.56 gun (or any full power rifle) as a home defense gun. I suppose a good compromise would be a subsonic 220 grain 300 BLK round that would likely not penetrate too far, but would majorly mess a bad guy up. A full ballistic test against walls using various guns is on my to-do list, but it will probably be the fall before I have the time to do it properly.

      • A subsonic 220gr .300 BLK is about the same mass and velocity as a .45 ACP, only in a ballistically-superior package. The sectional density will be better on a narrower projectile (.30 vs .45), so the .300 BLK would likely penetrate better than the .45 ACP.

        According to legend, the 40gr .223 HP rounds that are more safe than pistol rounds are safer because of their lighter construction and higher velocity. They begin coming apart into tiny fragments when they hit building material, and while the fragments will still come out the other side they drop energy more quickly than an intact round.

        Shooting a heavy slow round like a subsonic .300BLK *should* penetrate building material actually a bit better than a .45 FMJ of equal weight. If I was going to shoot .300 BLK or 7.62x39mm in the house, I would choose the lightest, most frangible and fastest bullet possible. I’m not worried about punching through a vest, I’m worried about energy deposition in the target, and if I miss, depositing as much energy as possible into the first wall it encounters so what comes out is less dangerous.

        Truth be told, there’s not much that beats a shotgun for home defense, unless you’re trying to penetrate body armor. Using subsonic rifle rounds doesn’t really buy you much over a pistol round of the same weight. In essence, making a rifle round subsonic only turns it into a pistol round.

      • Do you have or can you borrow a chronograph? I am really curious what the actual velocities/energies are and what kind of penetration/expansion is possible with such a short barrel.

  12. ” why are AKs so inaccurate at distance”

    “accuracy that AKs can only dream about.”

    My AK shoots just as well as my 556R. This “review” reads like a paid advertisement for Sig.

    Please stop with the nonsense about AKs being OMG HORRIBLY INACCURATE. Go stand 200 yards down range and let me take a shot if they’re so terrible.

    • I have had this issue with reviews here. There really should be 3 or 4 people reviewing the item to minimize bias.

    • I’ve had this issue with Jim Barrett’s reviews. He’s an admitted SIG fanboy, and his reviews reflect that. Also, by his own admission, he’s relatively new to this gun thing (he bought his first gun about 2 years ago). He’s learned a lot in a short period of time by throwing large amounts of money at the problem, but I’ve noticed from reading his articles over the past year, he doesn’t know quite as much as he thinks he does. (Note the long-stroke vs. short-stroke issue above.) In his “jumping in with both feet” practice, he’s bought (and sold) so many guns in such a short time that it makes me wonder if he actually gets a solid enough understanding about something to be writing a review on it before he’s off chasing the next new thing. That concern has been backed up on several occasions when he has said things that struck me as being very similar to the guy who repeats the stuff he heard at the gun store. Sorta like a much more detailed version of the “hit ’em anywhere with a .45 and they’ll fall down” or the “just rack the shotgun and they’ll run away” tropes. The combination of all the things above make me take anything he writes with a rather large pile of salt.

  13. I don’t agree with the author of this article. While I absolutely love my SIG 556R, it is only marginally more accurate than my AK-47; I think the 7.62×39 cartridge itself and possibly the barrel length play a part in some of the inaccuracy experienced with the platform. Still, my accuracy with my AK isn’t all that bad. It’s no precision rifle, but I’m confident I could get a kill shot in at 200 yards, maybe 300. If I need more accuracy at greater ranges that’s what a good .308 or 7.62x54r is for. I’m also not sure that he was correct about the whole long stroke vs short stroke thing. I’ve read previously that short stroke is more inherently accurate. I believe that’s why even the Russians themselves dropped the long stroke system and went to a short stroke system when they developed the Dragunov SVD.

  14. One of the reasons the SG 550 design is much more accurate than the AK design is the gas cylinder design. By anchoring it into the front of the trunion block, as the gas pushes the piston rearward, the resulting reactive force imparted to the cylinder head is transferred through tension to the trunion block, instead of pushing-on and flexing the barrel downwards. As parts heat up and expand at different rates, the slip-fit of the cylinder into the gas block also prevents adding flex forces to the barrel which would induce “stringing” of shot groups.

  15. As I understand it, and I am not expert by a long shot (pun intended), the things that make the AK not accurate or at least not any better than battle field accurate, are the exact reasons why you can drop an AK in the sand dirt muck grime etc etc and pick it up and it shoots. Loose tolerances so that crap can work its way out of the system. Guess the old saying is true….you can’t have your cake and eat it too.

  16. Am a police Officer. Enjoyed all your articles very much. Very informative. Keep up the good work and continue. Thanks.

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