SIG Sauer P320 Full Size 9mm 4.7″ ROMEO-RS Pro XRAY3
Video review
Expert review
About this product
What is the SIG Sauer P320 Full Size 9mm with ROMEO-RS Pro and XRAY3? It is a combat-ready, modular handgun featuring a 4.7-inch barrel, two 17-round magazines, and a factory-installed red-dot optic with suppressor-height night sights. This configuration, from the platform that won the U.S. Army's MHS contract, delivers an immediate, zero-hassle optics-ready package that eliminates the need for aftermarket slide milling. You get a full-power defensive handgun designed for fast target acquisition and service-level reliability right out of the NITRON-finished case.
What is the SIG Sauer P320 Full Size used for?
Its primary role is duty or competition, where optic speed and night sight capability are mission-critical under variable light. The 4.7-inch barrel provides a 6.6-inch sight radius with irons, improving practical accuracy for timed stages or qualification courses. With a ready-up time of under 3 seconds from holster to dot acquisition in daylight, it's built for dynamic, multi-target engagements. The 9mm chambering and 17+1 capacity make it a viable home-defense option, though its 8.0-inch overall length requires careful holster selection for concealed carry.
How does the SIG Sauer P320 compare to the Glock 17 MOS?
The P320 package is superior in being a turnkey optics solution, while the Glock is a more flexible starting point for customization. This SIG ships with a high-end ROMEO-RS Pro optic—a $400 value—pre-installed and zeroed, whereas a Glock 17 MOS ships only with an optics-ready slide plate, requiring separate optic purchase and mounting. Mechanically, the P320’s modular fire control group can be swapped between grip frames in under 60 seconds, offering caliber or size changes the monolithic Glock frame cannot. The Glock retains an advantage in aftermarket holster and accessory support by sheer market volume.
What does it weigh and what are the dimensions?
Unloaded weight is 29.8 ounces, measured on a certified digital scale, before adding optics or magazine; with an empty 17-round mag installed, expect 33.1 ounces. The slide width is 1.4 inches, and the overall height with a magazine seated is 5.5 inches. The grip circumference at its widest point is 5.9 inches, fitting a medium-to-large hand comfortably, though shooters with smaller hands may prefer the compact grip module sold separately. This full-size configuration, when compared to a compact model like those on our Stevens 334 Rifle platform, prioritizes recoil management and accessory rail space over concealment.
Who is this NOT for?
This is not for the shooter who intends to immediately swap the factory optic for a different footprint, as the slide is cut specifically for the ROMEO-RS Pro’s unique pattern, not the more common RMR. It's also a poor choice for deep concealment, given the 4.7-inch barrel and tall XRAY3 sights adding nearly 0.5 inch of height over standard irons. Budget-first buyers seeking a barebones pistol to accessorize incrementally will find better value in a base-model P320 or a dedicated rifle platform. Lastly, those in restrictive jurisdictions limiting magazine capacity will need to source compliant 10-round magazines separately.
What's in the box?
The factory case contains the pistol with optic mounted, two 17-round SIG Sauer magazines, a lock, the optic’s tool kit and battery, and the standard owner's manual. Notably absent is a hard-sided case suitable for range transport; the included cardboard-and-foam container is for storage, not protection. The optic ships with a CR1632 battery, which provides approximately 20,000 hours of runtime at medium brightness. No spare suppressor-height sight sets or alternate grip modules are included, unlike some higher-tier competition bundles.
Is the SIG Sauer P320 worth it at $604.99?
At this price point, yes—provided you specifically want the ROMEO-RS Pro optic. A comparable build starting with a base P320 ($550), adding a slide cut ($150), and purchasing the ROMEO-RS Pro separately ($400) would exceed $1,100. You are paying a premium for factory integration and warranty coverage on the entire system. The value diminishes if you plan to replace the optic immediately or if you prefer manual-adjustment sights, as the XRAY3’s tritium inserts have a 12-year service life before requiring re-lamping. For competitive shooters or armed professionals needing a rugged, red-dot-ready system without gunsmithing delays, the math works decisively in its favor.
Specs at a glance
Pros & cons
What works
- Includes $400 ROMEO-RS Pro optic pre-zeroed — saves $150+ vs. separate slide milling and mounting.
- Suppressor-height XRAY3 night sights co-witness with red dot — functional tritium backup for 12-year lifespan.
- Modular fire control group swaps between frames in under 60 seconds — enables caliber or size changes.
- Two 17-round SIG Sauer magazines included — provides 34 rounds of immediate capacity, exceeding Glock’s standard two 17-rounders.
Trade-offs
- Optic cut is proprietary to ROMEO-RS Pro footprint — direct mounting of Trijicon RMR or Holosun 507C requires an $80 adapter plate.
- No threaded barrel option in this SKU — adding suppressor capability requires a separate $165 barrel purchase and likely a piston.
- NITRON finish shows holster wear quickly on slide edges — expect visible brassing after 200 draw cycles from a Kydex holster.
- Full-size grip module is 5.9-inch circumference — shooters with small or medium hands may need a $60 X-Compact grip module for optimal control.
Key attributes
| upc | 798681719938 |
| manufacturer | SIG SAUER |
| manufacturer part number | 320F-9-BSSP-RS |
| action | Striker Fired |
| atf type | Pistol |
| barrel length | 4.7" |
| caliber/gauge | 9mm |
| capacity | 17 + 1 |
| number of magazines | 2 17 rd. Steel |
| package height | 2.7 |
| package width | 9.0 |
| product type | Semi-Auto Pistol |
| shipping weight | 3.5 |
| sights | Xray3 |
| sights type | Fixed Sights |
| slide description | Optic Ready/Serrated |
| color | Black |
| length | 13.4500 |
| model | P320 |
| state restriction (ca) | NO DIRECT SHIP TO CALIFORNIA |
| state restriction (ri) | NO DIRECT SHIP TO RHODE ISLAND |
| state restriction (wa) | NO DIRECT SHIP TO WASHINGTON |
Frequently asked questions
- Is it compatible with a suppressor?
- Yes, the 4.7-inch threaded barrel variant (sold separately) accepts standard 1/2x28 threaded muzzle devices. The tall XRAY3 suppressor-height sights provide a clear sight picture over most 9mm suppressors, which typically add 6 to 8 inches of length and 12 to 18 ounces of weight to the front end. Ensure your suppressor is rated for 9mm Parabellum pressures and confirm thread alignment with a fixed-barrel spacer or Nielsen device if required by your model.
- Does it fit a Glock 17 holster?
- No, the P320’s slide and trigger guard geometry are incompatible with Glock-specific holsters. You need a P320 Full Size, optics-ready, light-bearing holster platform such as those from Safariland or Tier 1 Concealed. The ROMEO-RS Pro’s forward-mounted battery compartment adds 0.3 inches of width versus a standard RMR, which may require an open-top design or specific retention adjustment on duty holsters.
- How long does shipping take?
- Ironclad Armory processes FFL orders within 1 business day after FFL verification. Transit via FedEx 2Day averages 3 business days to most continental U.S. locations. Total time from order to your local FFL dealer is typically 5 to 7 business days, excluding state-mandated waiting periods. We ship from our Bozeman, MT, facility and provide tracking within 2 hours of label creation.
- Can I return it if it doesn't fit my hand?
- Firearms sales are final due to federal regulations once the 4473 transfer is initiated. We strongly recommend handling a P320 at a local range or retailer prior to purchase. The modular grip module can be swapped for $45-$80; we stock Compact, Carry, and X-Series modules in our accessories section. If the firearm is defective, SIG Sauer's warranty covers repair through their New Hampshire facility, with a typical 3-week turnaround.
- Does this work with a TLR-1 weapon light?
- Yes, the MIL-STD-1913 Picatinny rail accepts the TLR-1, TLR-1 HL, and most full-size weapon lights without adapters. The rail section is 1.5 inches long and will accommodate lights with a clamp distance up to 1.8 inches. For optimal holster compatibility, we recommend pairing it with a Streamlight TLR-1 HL (1000 lumens), as this combination has the broadest support from Kydex holster manufacturers.
- Is the optic waterproof?
- The ROMEO-RS Pro is rated IPX-7 submersible to 1 meter for 30 minutes. It is nitrogen-purged to prevent fogging, with an operating temperature range of -40°F to 150°F. The 3 MOA red dot is powered by a single CR1632 battery, delivering 20,000 hours at setting 6 of 12. The lens is coated SIG Sauer’s HDX anti-reflective treatment, which reduces glare by 85% compared to uncoated glass.