Sig Sauer P320 Compact 9mm 3.9″ Optic Ready Black
Video review
Expert review
About this product
What is the Sig Sauer P320 Compact 9mm 3.9″ Optic Ready Black? It's a modular striker-fired service pistol configured for 9mm duty and concealed carry, featuring a PRO-cut optic-ready slide and SIGLITE night sights. Developed from the U.S. Army's M17/M18 service pistol contract, this variant prioritizes adaptability for civilian and professional users who require a platform that accepts modern red-dot optics.
What is the Sig Sauer P320 Compact used for?
This pistol is primarily used for everyday concealed carry and as a duty-sidearm platform. Its 3.9-inch barrel and 1.4-inch width slide provide a balance of concealability and muzzle velocity, yielding approximately 1,150 feet-per-second with standard 124-grain ammunition. The optic-ready slide allows direct mounting of popular micro red dots like the SIG ROMEO1Pro or Trijicon RMR, eliminating the need for milling, which is critical for shooters transitioning to electronic sights for faster threat acquisition.
How does the Sig Sauer P320 Compact compare to the Glock 19 Gen5 MOS?
The P320 Compact is better for shooters who prioritize modularity and a crisper factory trigger. Where the Glock 19 Gen5 MOS uses a single, proprietary MOS plate system, the Sig's PRO-cut slide accepts several optics directly, reducing height-over-bore by roughly 0.03 inches. However, the Glock 19 is 1.8 ounces lighter unloaded and has a more established aftermarket for holsters. For a user committed to the P320 platform's fire control unit swap capability, the Sig is the superior choice.
What does it weigh and what are the dimensions?
The pistol weighs 26.6 ounces (754 grams) with an empty magazine inserted. It measures 7.2 inches in overall length, 5.5 inches in height with the flush-fit 15-round magazine, and 1.4 inches in width at the slide. The grip circumference is approximately 5.7 inches, making it comparable in hand-feel to mid-size duty guns but 0.8 inches shorter in barrel length than a full-size Stevens 334 rifle is long.
Who is this NOT for?
This pistol is not for first-time shooters on a strict budget or those seeking maximum concealability. The 26.6-ounce weight is noticeable in lightweight clothing, and the modular FCU system adds complexity unnecessary for a simple range gun. Beginners would be better served by a more economical, fixed-platform option. It's also not ideal for competition shooters needing a longer sight radius; they should look at the P320 X-Five Legion model.
What's in the box?
You receive the complete pistol with one 15-round magazine inserted, a second identical 15-round magazine, a cable lock, and the Sig Sauer operator's manual. Unlike some competitors, it does not include an optic mounting plate kit, as the slide is cut for direct attachment. The total package weight shipped is approximately 3.8 pounds, including all documentation and packaging materials.
Is the Sig Sauer P320 Compact worth it at $508.99?
At $508.99, it's a competitive value for an optic-ready pistol with night sights from a major military contractor. A comparable Glock 19 Gen5 MOS typically retails for $20-40 more without night sights. The included SIGLITE sights alone represent a $100+ upgrade. For a shooter who wants a suppressor-ready host—often paired with a shotgun for multi-gun training—the out-of-the-box optic capability justifies the price point, saving $150-200 in aftermarket milling.
Specs at a glance
Pros & cons
What works
- PRO-cut optic-ready slide accepts SIG ROMEO1Pro/Leupold DPP directly—saves $200+ on milling
- Includes SIGLITE night sights (tritium/phosphor) with a 12-year service life
- Modular FCU weighs 7.2 oz—can be swapped to other frames/chassis in under 2 minutes
- DLC-coated barrel provides >10,000-round corrosion resistance with proper maintenance
Trade-offs
- 26.6 oz weight is 1.8 oz heavier than a Glock 19 Gen5—noticeable for deep concealment
- No accessory rail covers included—the Picatinny segment will chew up undershirts without a $15 cover
- Polymer grip module lacks aggressive texturing—requires Talon Grips or stippling for high-moisture use
- PRO-cut limits direct optic choices; requires adapter plates for popular RMR/Holosun footprints
Key attributes
| upc | 798681697441 |
| manufacturer | SIG SAUER |
| manufacturer part number | 320C9BSSP |
| action | Striker Fired |
| atf type | Pistol |
| barrel length | 3.90" |
| caliber/gauge | 9mm |
| capacity | 15 + 1 |
| color | Black |
| length | 10.5 |
| magazine included | 2 x 15-Round |
| model | P320 |
| number of magazines | 2 |
| package height | 2.8 |
| package width | 10.3 |
| product type | Striker Fired |
| safety | No |
| shipping weight | 3.2 |
| sights | Siglite Night Sights |
| sights type | Siglight Front & Rear |
| slide description | Optic Ready/Serrated |
| 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 the optic cut compatible with a Holosun 507C?
- No, not directly. The PRO-cut footprint is designed for the SIG ROMEO1Pro, ROMEO2, and Leupold DeltaPoint Pro. To mount a Holosun 507C, which uses an RMR footprint, you will need a C&H Precision or Springer Precision adapter plate, adding approximately 0.12 inches to the optic height. Always verify plate torque specs (typically 15-18 in/lbs) with blue Loctite.
- Does it fit Glock 19 holsters?
- Generally, no. The P320 Compact slide is 1.4 inches wide with distinct contouring, and the trigger guard geometry differs. It requires a holster specifically molded for the P320 Compact/ Carry models. We recommend holsters from Tier 1 Concealed, Safariland (RDS-compatible 7TS series), or BlackPoint Tactical for secure retention.
- How long does shipping take to an FFL?
- Ironclad Armory processes orders within 1 business day. Transit time via FedEx 2Day to most continental US FFLs is 2-3 business days. The total timeline from order to your FFL's notification is typically 3-5 business days, not including the mandatory 4473 background check hold period at your dealer.
- Can I convert this to a Flux Raider chassis system?
- Yes, the modular Fire Control Unit (FCU) is removable and compatible with the Flux Defense Raider chassis, as well as Sig's own X-Change kits. The serialized FCU drops directly into other P320 grip modules and chassis systems without requiring an additional FFL transfer, per current ATF ruling on the modular pistol system.