CALIBER 9mm Luger
GRIP TYPE Modular Polymer
FRAME MATERIAL Stainless Steel
FRAME FINISH Stainless Steel
SLIDE MATERIAL Stainless Steel
SIGHTING SYSTEM ROMEO1 Reflex Sight w/ Tall Contrast Sights
BARREL LENGTH 4.7 in (119 mm)
OVERALL LENGTH (IN) 8.0 in (203 mm)
OVERALL WIDTH 1.4 in (36 mm)
HEIGHT 6.3 in (160 mm)
WEIGHT (OZ) 29.5 oz (836 g)

Featuring SIG SAUER’s exclusive slide-mounted optic, the ROMEO1, the RX will ensure faster sight acquisition on target. Simply put, it will make a good shooter a great shooter. Shoot confidently with faster target acquisition and improved accuracy. Installed. Zeroed. And backed by the quality of the SIG name.

The P320 Full-Size offers a smooth, crisp trigger to make any shooter more accurate, an intuitive, 3-point takedown and unmatched modularity to fit any shooter and any situation. Its full-size frame is ideal for target shooting, home defense and any scenario where shootability and sighted accuracy are of the highest priority. This modular, striker-fired pistol features a full-size grip, full length slide, and choice of contrast or SIGLITE Night Sights. Available in 9mm. Safety features include a striker safety, disconnect safety.


The ROMEO1 features a molded glass aspheric lens with high performance coatings for superior light transmittance and zero distortion. Manual illumination controls remember your last used settings. Three MOA Red-Dot with multiple intensity settings ensures rapid target engagement under a full range of lighting conditions. The readily available CR1632 battery is top-loading, allowing for quick battery replacement without having to remove the sight from the firearm. Extremely strong and lightweight aircraft grade CNC Magnesium housing ensuring a lifetime of reliable service. Dependable waterproof (IPX-7 rated for complete immersion up to 1 meter) and fog-proof performance.” – Source”: Sig Sauer

Most firearms that I review I also own. Occasionally, I also get an opportunity to review firearms that I do not own, and in fact, may not plan to own. This is the case with the SIG SAUER P320 RX FULL-SIZE W/ROMEO1 REFLEX SIGHT.

The SIG SAUER P320 RX FULL-SIZE W/ROMEO1 REFLEX SIGHT is a range pistol that has seen quite a few rounds downrange and evaluating my experience with the ROMEO1 Reflex Sight was more intriguing than shooting the SIG Sauer P320  itself. You see, I am not a fan of reflex sights. My astigmatism has mitigated my use of ‘dot’ sights of most types regardless of how well they are made. With that said, I can recognize the value of these sights, as they do remove one part of the sighting equation – aligning front and rear sights to the target.

This review is not so much about the Sig Sauer P320 pistol as much as my experience with the ROMEO1 Reflex Sight, although I do have some input on the Sig Sauer P320 that you might find useful.

The P320 chambered in 9×19mm Parabellum was introduced in the North American market on 15 January 2014, followed by the .45 ACP compact model at the SHOT Show in January 2015.[1] On 19 January 2017, it was announced that a customized version of the SIG Sauer P320 had won the United States Army’s XM17 Modular Handgun System competition. The full-sized model will be known as the M17 and the carry-sized model will be known as the M18.” – Source: I would recommend that you peruse the provided link to learn more about the Sig Sauer P320 than I am willing to cover in this review.

My impression of the Sig Sauer P320X is favorable. Since I carried a Sig P220 in .45 ACP during my Leo days, I appreciate the Sig line of firearms, as the P220 provided its value and worth to me the days that I carried it. The Sig P320; however, is a striker-fired pistol and different characteristics separate it from any hammer-fired Sig pistol.

I found the trigger to be excellent and the pistol well-balanced. The grip was very comfortable in my hand and the pistol had a whisper of familiarity to it, as the grip angle and ergonomics are Sig-like in nature and I have traveled the Sig road before. There were absolutely no failures during running the pistol, in fact it ran like a top. This was all to be expected, of course. As I stated, my primary reason for running the gun was the optic system mounted on top of the stainless-steel slide.

I have had experience with reflex sights before, but they were not as well-built as the ROMEO1, hard to adjust, and did not last long under recoil. I have had several of these mounted on MSRs but removed them for my favored cross-hair optics. On a carbine, target acquisition was hard to beat, primarily because of the sold platform upon which they are mounted. On a handgun, although they may be mounted securely, the platform is not the most solid; wherein, the platform being the shooter holding the pistol. With that said, let’s first take a look at the ROMEO1 features:

  • Molded glass aspheric lens with high-performance coatings for superior light transmittance and zero distortion
  • 3 or 6 MOA red dot with multiple brightness settings for rapid target engagement under a full range of lighting conditions
  • TruHold™ Lockless Zeroing System that utilizes twin adjustment springs designed to endure handgun recoil and return to zero shot after shot
  • New point-source emitter provides exceptional brightness with 12 settings (10 Daytime/2 NV), and 20,000+ hours of runtime
  • MOTAC™ (Motion Activated Illumination System) that powers up when it senses motion and powers down when it does not
  • Aircraft grade CNC Aluminum housing ensures a lifetime of reliable service
  • Dependable waterproof (IPX-7 rated for complete water immersion up to 1 meter) and fog proof performance
  • Ruggedized protective steel shroud included for extreme durability
  • Easy access battery compartment
  • SIG SAUER® Electro-Optics Infinite Guarantee™ and SIG SAUER Electronic Component Limited 5-Year Warranty

Turn the sight on by momentarily pressing either the up-arrow or down-arrow power selector button.   To turn the sight off, press and hold either the up-arrow or down-arrow power selector button for 2 seconds. The sight will remain off until you momentarily press either the down-arrow or up-arrow power selector button.  When the sight is turned back on, it will return to the last brightness level used.

After 2 minutes of inactivity (no movement), the sight will enter its power saving mode and automatically shut off. 

Any movement will immediately turn the sight back on, returning the sight to the last brightness setting used.  The ROMEO1 has 5 illumination settings, 4 daytime and 1 NV.  To increase the intensity of the 3 MOA dot, press the up-arrow button on the left side of the sight.  To decrease the intensity of the 3 MOA dot, press the down-arrow button.

In the case of the pistol that I was running, the POI was low to my POA. This was a range pistol and I did not want to adjust the sight to my preference, and I ended up doing a lot of sight compensation. Adjusting elevation and windage is accomplished by turning two adjustment screws; one for windage (right side) and one for elevation (top) with a flat-tip screwdriver (an adjustment tool is provided with the pistol but was not available to me).

The first thing that I had to get used to was viewing the red dot quickly. That is, getting the sight in front of my face so that the red dot can be viewed. This takes a different technique than what I am used to with open sights. Once in my line of vision; however, the dot remains for viewing until I lower the pistol. My challenge was to keep muzzle flip at a minimum and follow through with my shots to keep the dot within view.

I find the dot more challenging than with open sights. I ran the pistol through a series of Mozambique drills, which at some point in the exercise, forced a reload. Unfortunately, I only had one magazine. This resulted in more practice than I wanted getting the “sight picture’ where it needed to be.

Being that the sight was not adjusted properly meant that I spent most of my aiming time attempting to compensate for the difference of POA to POI. That is not a fault of the sight, and I compensated well enough to successfully place quite a few shots to the heart and all but one to the head (does a Carotid artery hit count as a head shot?). To give you an idea of how far the sight was off, I had to aim at the ‘7’ in the silhouette target to hit the ‘8’ that was below it. I am talking several inches at 10 yards. The time was well spent; however, working on heart-to-head transitions.

The combination of Sig Sauer P320 and the Sig ROMEO1 sight seems to be a good combination for those who like or need this type of combination. Do not expect rock solid viewing of the dot, however. As I mentioned, the foundation of this platform is the shooter and I am not the steadiest of shooter. I do better with open sights, because I do not see the movement of the sights as much as I see the movement of a dot. I do tend to try and rush the shot with a red dot (or laser). And, of course, the viewing of the red dot is more unstable with a pistol than with a carbine. Then, there is the question of carrying a pistol with a dot sight.

I watched one video from Sig Sauer where the presenter stated that dot sights were the future and that he could see in five years all pistols having them. If I was paid to promote dot sights, especially being a trainer with Sig Sauer promoting dot sights, I would promote them as well. However, while I can endorse them, I cannot promote them except for certain situations.

The sights that come with the P320X are high sights and you can view the front sight through the RMR. The dot is also co-witness with the front sight. If the reflex sight fails, you have the open sights as backup. The open sights are Sig night sights. If you are coming up out of bed in the middle of the night to respond to a situation, a quick press of either illumination control of the sight activates the dot. Depending on your last intensity setting, the dot may be too low or too bright. You must then adjust the intensity. The darker the environment, the lower the intensity should be to prevent distraction from too bright a dot. In a home situation, I like the idea of the dot sight.

If you are involved with tactical types (law-enforcement, military, security, etc.) a mounted dot sight is a given and I can really see the need of one being mounted on your duty pistol and or carbine. For competitors, a RMR is a very good thing, and I have seen some very fast times (from video) using these devices.

For us citizens who carry concealed or open, I really question the wisdom of carrying a pistol with an RMR. Now, there are those who would do it for effect and to be ‘tacticool’. I carry a 1911, and it can be a handful to conceal at times. Add an RMR and my life just got more complicated.

Unless you are carrying the pistol/sight combination in an open-holster on the waist, thigh, or tactical vest, the concealing of such a platform would be a waste of time, although I am sure that somebody will attempt to do it. I am not saying that it cannot be done, but I am asking why it needs to be done except to prove a point.

Consider that if we have to pull our firearm in a defensive situation, we may or may not even have enough time to use the sights let alone press a button to turn on a dot. If the pistol has a thumb safety, such as on a 1911, the thumb safety is wiped off during the draw stroke and the pistol is ready to fire once the sights are aligned (or before). I have trained to do that, and it is second nature to me. Add in the extra motion necessary to illuminate a dot, well…

So, here is where I am at regarding dot sights; they are good under certain situations and when there is enough time to prepare them for use. They provide quick target acquisition and can be an aid for those with disabilities. Otherwise, they are a hindrance.

So back to the target of this review, the Sig Sauer P320 RX Full-Size w/ROMEO1 Reflex Sight. What you get is an excellent 9mm platform carrying 17+1 rounds of your favorite 9mm fodder; a fine pistol equipped with some serious sights once fully equipped with the ROMEO1 Reflex sight (or your sight of choice). Materials-wise the P-320 X breaks down primarily into polymer and steel. The grip module is made of polymer finished with stainless steel. The slide is made of stainless steel finished with Sig Sauer’s Nitron coating to resist rust and corrosion, and the barrel is made of carbon steel. Depending on how you look at it, the P320 is either the crème-de-la crème of handguns or just another pistol. MSRP is $728 (source: Davidsons) for the pistol. At the time of this writing the Sig Sauer ROMEO1 PRO Reflex Sight 1x30mm 1 MOA Adjustments MOA Dot MSRP is $479.99 – $509.99 but can be found at Midway for $399.99 – $419.99 (depending on selected options) with free shipping.

I can recommend the Sig Sauer P320 RX Full-Size w/ROMEO1 Reflex Sight for those who want or need such a combination of pistol and electronic sight. I like it for some fun range time. In real-world situations; however, I still prefer a good set of open sights.


P320 RX Full-Size:


About Taurian

Taurian is a U.S. Army veteran and former LEO and Defensive Tactics Instructor. Taurian also has over fifty years of experience as a Technical Writer and Training Program Developer. After leaving home at the age of ten without any shoes, Taurian continues on with many years devoted to the keeping and bearing of arms.

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