There’s a growing trend for concealed handguns: put a red dot on it. As the cost and size of red dot optics come down it’s becoming economical for the average shooter to mount a red dot sight on their pistol. But a challenge remains: finding an affordable optics-ready handgun. Or a handgun with a pre-mounted red dot sight. SIG SAUER has a prescription for that: the P320 RX.

Lest we forget, the SIG SAUER P320 is a modular handgun. Throw a lever and push a button and the firearm that started life as a full-size .40 or .357 SIG man-stopper transforms into a compact and concealable 9mm carry gun. P320 replacement frames and caliber exchange kits don’t even require a trip to the FFL; SIG ships them straight to your door. The P320 RX Compact is the rallycross version of the P320.

SIG SAUER ships the P320 RX Compact with a slide pre-cut for red dot optics, pre-installed with a ROMEO1 reflex sight. The ROMEO1 is their smallest optic, roughly the same size and feature set as the Leupold Deltapoint or Trijicon RMR. A couple buttons on the side control the dot’s brightness.

It’s powered by a watch battery that can be swapped-out through a top-loading cassette. As watch batteries don’t tend to last very long, SIG SAUER added a motion sensor that turns the dot off when the gun isn’t moving — and turns it back on when it detects motion. Right answer.

On this firearm, the P320’s iron sights have been swapped for suppressor-height sights, to enable co-witnessing the red dot and iron sights. Everything is aligned. Should the red dot suddenly disappear, you can swap from the electronic aiming system to the iron sights without a moment’s hesitation. To that end, the ROMEO 1 optic has a slot machined into its base to make the suppressor height iron sights visible through the window.

The optic is great for shooting, but complicates carrying, increasing the P320’s height significantly. At the same time, the SIG is a chunky old thing with a rather tall snout, larger than most entrants in this category. The combination of the tall slide, suppressor-ready sights and an under-barrel Picatinny rail renders the P320RX Compact’s snout decidedly John Goodman-esque.

There are RX Compact compatible holsters (such as the 5.11 model above), but not many at the moment. And they aren’t what you’d call discreet, especially for a gun that bills itself as concealed carry firearm. Tyler Kee sometimes totes his red-dotted S&W in an appendix carry holster without printing, so there is that. But then Tyler is a ridiculously thin bastard.

Out on the range the gun handles well. I’m a fan of the P320’s ergonomics and trigger and this example is no different. The pistol is easy to point, has plenty of space to get a proper grip, and keeps recoil to manageable levels. All of the controls are well placed. It’s a great gun.

Accuracy isn’t hampered in the least by the shorter barrel. These five rounds were fired from our usual 30 foot distance by yours truly using the red dot for aiming with exactly zero adjustment — the sights were dead-on from the factory and required no fine tuning. Ignoring the one flier to the left, the gun stacks the rounds right on top of each other on the target. For a carry gun that’s a major win in my book.

A number of gunmakers (e.g., FN, GLOCK and S&W) offer “optics ready” firearms. They all require that you buy, mount and zero a separate optic. SIG SAUER’s P320 RX Compact is the complete package, ready to rock-and-roll straight from the factory, sold for a reasonable price. If you’ve decided that it’s time to carry a handgun with a red dot optic, this is the easiest way to get in the game. And the chances are, you’ll stay.


Barrel: 3.9″
Overall length: 7.2 inches
Available calibers: 9mm Luger
Weight: 25.8 ounces
MSRP: $799

RATINGS (Out of Five Stars):

Accuracy: * * * * *
The gun is accurate enough to stack round on top of round at 30 feet.

Ergonomics * * * *
For handling on the range the gun is great. The grip grabby while not abusive, the controls are well placed, and the overall feel of the gun is solid and sleek. As you’d expect, carrying is a bit more difficult due to the added height of the red dot.

Reliability * * * * *
Hundreds of rounds through this and other P320 models without a single issue.

Overall * * * *
Less effort and expense than anything else on the market, built like a tank, with the modern styling we’ve come to expect from SIG SAUER. Dropping a star for the excessively large snout, but otherwise a damn fine option.

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54 Responses to Gun Review: SIG SAUER P320 RX Compact

  1. Is a red dot really necessary at self-defense distances? Laser seems like it would be the superior solution for several reasons.

    Also, if the red dot has a motion sensor for battery savings, how will it differentiate from normal body motion during on-body carry?

    • Lasers require a lot more power, which means an “always on” or “motion detected” activation would kill your battery in a hurry. A switch on the gun to activate the laser is another potential point of failure, and lasers tend to be quite a bit more expensive than red dots.

      Lasers have their attributes, too. They allow shooting from any position without putting the gun up between you and the target. It’s good to have options.

    • “Laser seems like it would be the superior solution for several reasons. ”
      Speed on target isn’t one of them. I’ve tried it myself, along with several other people, and really proved, at lest to all of us trying the drill over a course weekend, that the laser was slower than iron sights to get a round into an 8″ target at 15 yards.

      • I can believe that. Red dots wouldn’t do any better, however, right? The RDS isn’t on target until your iron sights are, and vice-versa.

        • Sort of.
          Theoretically, if your red dot is on target, so are your sights. But the red dot doesn’t require that your eyeball be directly in line with those sights.

          Additionally, you can aim a red dot with both eyes open and your focus on the target. In theory you can also do that with iron sights, but with limited accuracy.

        • Red dots are as fast or faster for most people. The problem with the laser is that you are looking for it on the target and it takes a second to find. The red dot is right there and is on the same focal plane as the target.

        • Curtis said:
          ” In theory you can also do that with iron sights, but with limited accuracy.”
          Not just in theory, I’ve put it to practice as the only way I have trained for my entire four or five years of gun ownership. I didn’t know any better when I started so I have always been a target focus shooter with both eyes open. And my accuracy isn’t affected. I’ve tried closing my off eye to focus more but it hasn’t seemed to make a difference. It only slows me down.

      • The only laser I want will be a night vision to supplement an NV scope on my suppressed 300 BLK SBR.

        That’ll be a while since my recent misfortune sent me truck shopping and I exercised my right to middle age crazy by going all out for the F150 4×4 Lariat Super Crew. Ouch! Nice ride though. Bought it yesterday.

    • I think lasers are the right answer generally, but there’s a school of thought championed by Gabe Suarez and others which says red dots on handguns is the right solution. I get their argument and it makes a lot of sense but I generally come down on the “laser or iron sights” side.

      There’s no differentiation between “normal” body motion and “combat” motion, so the dot is indeed on when you’re moving. Or even just driving around in a car. But for when it’s in your nightstand safe or when you’re sitting on the couch doing nothing it should be off. SIG SAUER does not say that the optic turns off when pointed down, and after 30 minutes of testing here at home I can confirm that it stays on.

      I guess the real benefit is that if it’s in your safe it will turn off and save battery power. So if it’s a nightstand gun then it should work pretty well.

      • Fair point – the sleep function does depend on how active one is. Even so, battery life is good even if left on all the time. You just need to remember to change batteries on a regular basis. 😉

        The downsides to a laser for me have been that grip-based lasers can get blocked by my hand accidentally and I’ve found lasers are harder to see at distance and are susceptible to variances in lighting conditions.

        By comparison, the red dot is easy to find, doesn’t get blocked and is always bright. With different dot sizes available one can choose a size that suits the application better as well.

      • I’ve pulled dead optics and dim lasers out of my safes and nightstand. Seems motion sensors need a trickle of electrons to remain conscious. Certainly a trade off. But my performance bar for personal protection is a little higher than “should work pretty well.”

        That said I have an RMR and DeltaPoint Pro both of which I love. But careful with the feature generalizations. They look similar but the differences are many.

  2. If the red dot sight is motion triggered, wouldn’t carrying it result in it being on much of the time, and therefore quite likely to be dead when needed most?

    Or does it stay off when pointed down?

      • Aimpoints have battery life measured in months if not years. Those are a very different design, however. The Romeo is more of a holo sight, and more comparable to an EoTech, I would think. My guess is that batteries do not last long at all, when the red dot is activated, but I’m sure someone with decent google-fu could get the actual published statistics from Sig’s website.

        • I can’t find it on their site anywhere. Because of different intensity settings, and the fact that it turns off, I’m guessing battery life is extremely variable. Still, I’d like to know what a mid level intensity, constant-on run time would be.

    • Having both, I do prefer the RMR. It is hard to argue with the price of the ROMEO1 when bundled though – that is why I have both 😉

  3. This is neither here nor there, but I picked one of these at Cabelas the other day, on sale, with a coupon, and with a trade factored in. So pretty much $699.99. It’s the Cabelas exclusive with the bare stainless slide (two-tone), and it only took a couple days for me to realize I wouldn’t be able to live with the stainless slide, so it’s already off to SIG for a refinish in Nitron. Should have it back in 6-8 weeks. Considering the retail (one LGS) and online prices I’ve seen, and that it’s only in stock right now at one place online that I could find, for $879.99, I think even factoring in the refinish I’m coming out ahead, or at least break even. Solid gun, by the way.

  4. Having choices is wonderful. Hanging more stuff on a firearm would not be a choice I’d make for potential home/self defense, other than the light on my shotgun. I like it simple, lean and clean.

    • I am generally of the “keep it simple” school of thought myself.

      The nice thing about a setup like this, is even if the battery is dead you can still aim and shoot the old fashioned way. The co-witness feature is critical to me.

  5. When reviewing a polymer handgun I would recommend a 20 round target shoot test. I once shot 20 rounds at about a 6 or 8 sec. rate, at 15 yards using sand bags and bench rest, with my 5″ polymer 9mm. The first 6 or 7 rounds were tightly grouped (maybe 1.5″ average) and then the impacts really began to drift. By round 20, the impacts had drifted about 5 inches (left and down a little).

    Now my (nameless) 9mm has metal slide guides up front and plastic slide guides in the rear, so I’m guessing that the Sig here is better because I can see from the picture that the 4 guides are all contained in the metal subframe. Still, the thermal expansion coefficient of any plastic is huge compared to any metal, especially steel. So my next handgun purchase going to be steel framed.

  6. The purpose of sighting aids like the red dot is to turn average shooters into experts. The question is what level of expertise is required defend yourself. The data seems to show that that answer is that most people can get the job done without the red dot. Therefore. I consider the red dot a defensive pistol an unnecessary pice of gear.

      • Yes they do but they are still successful with an insignificant amount of collateral damage. Do you think a red dot will improve hit rated against moving targets when the primary cause of the miss is a poor understanding of deflection shooting?

    • The data also shows most gun owners are content with mediocrity. Does that mean the rest of us shouldn’t bother pursuing excellence? The use of the word “need” tells me everything I need to know about how you think. I prefer to think in terms of “want” and the never ending pursuit of improvement.

  7. Auto off/on is the wrong solution for a defenive red dot. Trijicon figured out how to make the battery last forever and I’m sure sig could too.

    Yet another factory red dot compatible handgun with the dot and rear buis in the wrong position. Nothing says enjoy the benefits of single focal plane shooting like a misplaced rear sight to muck it up. For the life of me I can’t figure out who they have designing these things.

    • I’m confused by your comment. What is the ideal arrangement then? I think the RX setup is just about ideal. It’s nothing new… The same arrangement as an M4 with a red dot and cowitnessed iron sights.

    • DM, I think you are missing the function of co-witnessing. The idea is to let your familiarity with sight alignment guide your eye to the dot. Then you can choose to transition your focus to the dot alone if that’s what the situation calls for. It doesn’t prevent you from experiencing the benefits of a single focal plane.

      • No offense mike, but I believe you to be misunderstanding the benefits of a red dot. (Rocky this should answer you as well) A red dot is the primary sighting system. Iron sights are to be backup, hence the term buis. On rifles they fold so as not to interfere with the way our eyes work. Since common handgun sights cant fold, the rear buis should be in front of the red dot. Red dots allow us to focus on the threat, something humans naturally do when under stress. It allows us to work with as opposed to fighting against our natural biology. When the rear sight is behind the red dot, our eyes automatically take the short cut many of us rely on to gain a slight speed advantage, glancing at the rear sight as we draw, then using that as a reference point for sight alignment. The best way to use red dots to their max effeciency is to use just the dot and maintain a threat focus through the entire draw and presentation. The backup iron sights are there to do simple that, backup the optic in the event of a failure, they should be placed appropriately.

        • DM, I think what you are missing is the difference between alignment with a stocked rifle and a pistol. On a rifle, the biomechanical alignment (gotta use a Haley term when I can!) created by the 4 points of contact (shoulder, cheek, and 2 hands) puts the dot in front of the eye reliably without any other assistance needed.

          With a hand gun, there is basically one point of contact (2 hands at the same point). Yes, competition shooters with a lot of practice may not need help, but most people find if they only have the dot it slows them down because they are used to aligning the front and rear sights. So initially you align on target based on the 2 points of reference. Then your eye shifts to the dot. As you practice you start going to the dot faster and ignoring the irons. Of course, they are always there if you need them as a backup. I’ve never tried it with the rear sight in front of the red dot, but I would think it would not offer an advantage and be a detriment because it’s unfamiliar. Here’s a longer discussion of the issue:

        • Mike,
          I love the use of a Haley term, guy knows his stuff. I read the article and it seemed to only tackle the supposed advantages (neither of which I used to make my case) while also admitting that training scars contribute to the learning curve being so large with buis in front of dot setups. If we trained properly from the start, we wouldn’t rely on the shortcut and the dot would provide maximum benefit much sooner. With the dot sandwiched between the irons the only benefit available will be the precision at distance and the low light sight aquisition, you lose the increase in speed almost entirely. I would rather put in the extra reps to make the dot as effective as possible than short cut it and miss a large portion of the benefit.
          Check this out for a better more in depth explanation from a man much wiser than I.

          Ps. I appreciate the civil and reasonable discussion, unfortunately that is all too lacking these days and its one of the best ways for growth in knowlege.

  8. “…the SIG is a chunky old thing with a rather tall snout, larger than most entrants in this category…”

    Compared to what? A Glock 19 is probably the smallest entry in the compact pistol market. And the P320 Compact is within a tenth of an inch in most dimensions except height where it is two tenths IIRC.

    And that is just comparing the specs, holding them side by side they are nearly the same size.

    • Enclosed volume of the Sig, is meaningfully larger than the Glock, even if the dimensions of the smallest box they’ll each fit into doesn’t look too different. Kind of like a J frame is much “smaller” than a Glock 26, simplistic measurements be damned.

      • Even if you are talking about volume the differences are along probably less than 5%.

        I’ve personally found the real difference in carry ability is in the holster. A good holster well fitted to a person’s body type along with the proper sized gun has more to do with the ability to conceal a gun than small fractions of an inch of gun size.

        People spend too much time on tiny nitpicks instead of things that actually matter.

  9. Learn how to shoot fast without jerking the trigger and don’t worry about fancy sights, lasers, red dots, et cetera. Master proper trigger control and you’ll hit what you’re aiming at without using the sights much at all.

    • For defensive shooting at ranges of 1-7 yards, trigger control be damned: Learn to hold the handgun tight, make it immovable. Then you can squeeze or slap or jerk the trigger, but the barrel and sights won’t move. (That’s paraphrased from Rob Leatham, by the way, on combat style shooting.) Now if you also have a smooth fast constant trigger pull/push, fine. All the better.

  10. Did you ever bump those side buttons unintentionally? Seems like a bad design…

    To answer another post, no–a red dot is not “necessary” at self defense distances. However, nothing else compares when you need to make a precise head shot or hit at distance. It gives you more options without a trade-off, something a laser can’t do.

  11. Out of curiosity, is any department of any size issuing service weapons with red dot sights yet? If the darned things do make a measurable contribution to operator accuracy and efficiency, belt carrying cops ought to be the first to benefit. The lack of police takeup despite supposed advantages, were a contributor to deflating the hype bubble surrounding lasers a decade or so ago.

    • I’ve seen plenty of indications of smaller departments that are allowing it if the officer wants to fund it, but I haven’t heard of any departments issuing it yet. I would expect the institutional inertia will resist it for various reasons for a while. Pursuit of Excellence is not a common denominator among the average officers on the street, and it’s certainly not the priority of most bureaucrats!

  12. I’ve tried everything, but the Viridian ECR technology is by far MY choice. On when you draw, BRIGHT green, so bright it literally lights up things around it, off when in the holster.

    • I understand why you made the choice but how much training have you done to validate that decision? Ive seen quite a few guys adopt such a thing and then abandon it after training. IMO a bright white light is a far superior device to mount to a self defense firearm. Due to the way the human eye tracks motion upon recoil in low light your eyes will be prone to chasing the visible laser. Plus you lose the ability to search or maintain light control that you could with a proper white light.

  13. I don’t understand the hoopla surrounding the Sig P320 product line, another striker fired polymer pistol…yawn. Why not just buy a Glock? On the other hand the nearly identical but infinitely more practical and affordable Sig P250 is something to get excited about, at least for me. True DAO with restrike capability and at least $100 less expensive. It just doesn’t get the love and press coverage the 320 does.

    • I couldn’t agree more. Also, there are still people out here who do not like striker-fired guns. Period. I am convinced that the no-frills, easy to operate, hammer-fired P-250 is a better choice for CC (the only “frill” on it should be its glowing sights that make it easy to find in the dark when using it for home defense). I have one in full/subcompact and I carry it in an IWB holster with no problems.

  14. I received my P320 RX Compact last Saturday. Took to range on Sunday and found my shots are all over the place at 10 yards with the iron sight. Upon further investigation, the front sight was very loose. I was able to push with my thumb left and right easily. And apparently the RDS was sighted with the front site off centered. Called Sig customer support and told to send in the upper. Somewhat disappointed….

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